


Sea Spirit

by destieljunkie



Category: Supernatural
Genre: AU, Angst with a Happy Ending, Attempted Rape/Non-Con, Bottom Dean, Destiel - Freeform, Dominant Castiel, Emotional Hurt/Comfort, Explicit Sexual Content, Interspecies Romance, Interspecies Sex, Legends, M/M, Masturbation, Mating Cycles/In Heat, Mermaid! Dean, Merpeople, Persecution, Physical Abuse, Scientist! Castiel, Self-Lubrication, Sexual Abuse, Violence
Language: English
Status: Completed
Published: 2013-09-29
Updated: 2014-01-19
Packaged: 2017-12-27 21:59:30
Rating: Explicit
Warnings: Rape/Non-Con
Chapters: 25
Words: 60,500
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/984094
Author URL: https://archiveofourown.org/users/destieljunkie/pseuds/destieljunkie
Summary: <blockquote class="userstuff">
              <p>A disturbing childhood experience haunts Dr. Castiel Milton so profoundly it shapes his entire career and even his very existence. He has spent many years trying to find evidence of the elusive spirit of the sea that once saved him from drowning.<br/>Decades later he must confront memories of a distant past when a chance meeting pushes him to accept there could be some truth to the ancient legend of the people in the water. Castiel is pulled into a story where myth and reality become one and the same. He must trust in his heart and rescue the man he loves from torment and death.</p>
            </blockquote>





	1. Affirmation

**Summary for the Chapter:**

> Dr. Castiel Milton has carved out a productive life for himself as a prominent marine biologist. A life decided by a chance meeting many years ago when he was saved from death by a stranger who lived in the water. Castiel spent a lifetime wondering if the encounter was a memory or his imagination. One day a reliable witness arrives at the institute with some compelling evidence that leads him back to the sea.

**Notes for the Chapter:**

> An Inter Species Love Story

**Affirmation**

The scratchy video tape flickered in and out of focus. The images were indistinct and grainy, but there was definitely something there. Dr. Milton leaned forward, tapping his pen against his mouth while he narrowed his gaze and stared at the screen. He shook his head, struggling to process what he just witnessed. He hesitated when he slid the glasses from his nose and rubbed at the space between his eyes.

“I don’t think I would be able to categorically confirm or deny your claim just based on the evidence you've presented here.” He spoke the words slowly, trying to stay professional. Beneath that calm surface, he was desperate to know more. “It’s certainly compelling. I appreciate you taking the time to bring this to our attention. Please come back if you manage to record anything else.” Castiel offered. He shook the man’s hand and helped him to the door.

“Thank you for your time, Dr. Milton.” The visitor replied, preparing to head out the office with the video camera resting under one arm.

“Castiel, please.” Dr. Milton responded, with a warm smile. “If you could wait in Reception. I just want to confirm the co-ordinates, if that’s alright.”

“Of course. Thank you again.” His eyes darted over to glance at the other man sitting with his back to him in one corner of the office, still making notes on a pad of paper. The man nodded once more and backed out the door while Castiel held it open, waiting until he could hear the sound of feet padding down the stairs before he turned to his colleague.

“Well.” Castiel exhaled. “What do you make of that?” Marshall looked up from his work and couldn’t help his mouth from curving up at one corner. Castiel knew what that look meant. His friend had seen _something_ on that tape. Something that could be a key point in their careers and help put the institute on the map, once and for all.

“You already know what I think.” Marshall answered calmly. Castiel nodded.

“I know, but it’s a little soon for us to be making judgements like that. I’ll go get the co-ordinates and take it to the CSO. If he thinks it’s worth a look, we’ll head out in the morning.” Castiel suddenly stopped and turned to his friend. He looked concerned. “Marshall, don’t say anything yet. We can’t afford this to go public.” Marshall grinned at him. He looked almost predatory when he swivelled round on his chair and pushed himself up from the seat. He walked over and patted Castiel hard on the back.

“Do you honestly think I want anyone else taking the credit for this?” He laughed. “Castiel, this could be the discovery of a lifetime. Why in the world would I risk having to share that?” Castiel relaxed a little and huffed a laugh of his own in response. He was trying hard to suppress the excitement rising up through his body. He nodded back with a smile.

“Right, don’t start without me. I just need a few minutes.” Castiel added, before running after the witness. Marshall could hear his footsteps fade away while he replayed the copy of the video he made from the original, shaking his head in amazement when the sleek body of something in the water swept past the lens. The graceful way it moved suggested it was familiar with the deep trenches under the waves. His thoughts became quickly consumed with the idea of capturing and identifying something the world had never seen before. He knew what Castiel would say about that, so he decided not to mention it. As if on cue, his partner reappeared in the doorway, holding a piece of paper between his thumb and forefinger.

Castiel was smiling even more when he deposited it on the desk, gaze soon drifting back to the section of tape Marshall was playing on a loop on the desk monitor. Whatever it was seemed to swim like a mammal, but there might have been a definitive purpose to the fluttered movements caught on film. Castiel felt another surge of excitement swell inside him when he considered the possibility he had finally found what he'd been looking for since he was a boy.

That one misty day on the beach at Winter Harbour when he was eight years old had shaped his life, his career, and his perception of the world. Castiel never stopped believing, hoping. He knew what he saw that day. The image was locked in his memory. A pale hand rising from the swirling tide to cast his discarded pebbles back to him. He remembered the first time he saw the other boy break the surface of the ocean with a playful twist of his smooth blue-grey body when he cavorted innocently between the break waters. Castiel could still recall the event clearly. He would never forget it. No one believed him, of course. His father had just laughed and ruffled his hair, but he never accepted his story about the beautiful boy in the water. His mother never said much of anything to anybody. Castiel thought she never seemed all that interested in him anyway.

He had spent a long time trying to forget how lonely he felt as a child. His senses snapped back to reality when he realized Marshall was calling him.

“Sorry. I was just… sorry.” Castiel shook his head and tried to focus on the present, continuing to watch the film from the corner of one eye while he was daydreaming. He blinked. “I'm really hopeful this time.” Castiel said softly, and Marshall nodded while he studied his friend's expression. Castiel had never shared his childhood experiences with Marshall, but he had always known how passionate he was about finding a live specimen. They were scientists. The discovery of something entirely unknown was more important than anything he could imagine. His thoughts were drifting again. Marshall clicked his fingers in front of Castiel’s face.

“Come on.” He prompted, with a gentle nudge to his elbow. "Take it up to the first floor and see what he says. If he agrees, we need to make some preparations.”

Castiel gathered up the paperwork from his desk. He impatiently pressed a button on the computer and waited with his hand out until the disc popped out with a click and dropped into his palm. He shoved it into the pocket of his lab coat and slid a pen behind his ear. Castiel could hear Marshall still flicking through the case file when he closed the door behind him.

_____

“I am serious, yes.” Castiel repeated. He was standing opposite a large desk and staring at the CSO, tapping his foot in agitation. He already stated his key points several times and played the video twice. Castiel was still waiting for a decision.

“Hmm.” The chief officer mumbled, surveying the meticulous notes Castiel had produced. He always presented his reports well. Marshall was convinced his partner had OCD, and told him so on a regular basis. Castiel knew it was actually because he was a perfectionist. His CSO leafed through the file again. He held up the stills to the light and narrowed his eyes. “I'm not certain as to what you have here, Milton.” He said, after a long pause. “But it would appear this may benefit from further investigation.” Castiel held his breath and tried not to scuff the carpet. The time seemed to pass painfully slowly. Castiel watched the man’s eyes flick up at last to meet his own. His boss actually smiled and dropped all the documents on the top of his desk with a sharp slap. “Okay.” He grinned, and Castiel felt all his muscles relax. “I’ll fund one month, initially. You, Marshall and maybe two or three others. From your department or a freelancer, I don't care. You can pick the team, Castiel. Preliminary observations only. Documenting evidence, photographs, that sort of thing.” He suggested. Castiel nodded enthusiastically and couldn’t resist another smile.

“Of course, sir. Thank you.” He tilted his head in acknowledgement. “I'll gather a team and set off in the morning. You'll get a regular progress report, of course. If initial observations look promising, I may consider setting up an ongoing project. If that’s okay with you, sir.” Castiel added quickly. The CSO shrugged.

“You have a graduate degree in marine biology, Milton.” He said, after a pause. “I trust you to make an independent decision. Do what you want. As long as you can pay for it, I have no objections.”

“Thanks.” Castiel replied. That was a rare compliment.

Castiel pushed the door open with a little more force than Marshall was expecting. He jumped in surprise when Castiel tumbled into the room with a wide grin that made his blue eyes sparkle. Marshall suddenly realized why he was so happy.

“You got it?” He asked hopefully.

“One month.” Castiel breathed through his smile, depositing the paper folder on the desk at his station.

“Yes.” Marshall was barely able to contain the thrill of anticipation rushing through his veins.

_____

The dawn came early. Castiel had hardly slept. He poured out yet another coffee, yawning when he rubbed the back of one hand across his eyes. He was alone in the office. Castiel walked slowly over to the computer, mug in hand. A curl of steam rose from the edge of the cup when he sat down in front of the screen. He typed the co-ordinates into the program and waited for the others to arrive. As the data started to load, his mind was once again cast back to the mysterious experiences that effected him so profoundly as a child. He closed his eyes, subconsciously replaying them in his head. They had haunted his dreams and even his waking moments for as long as he could remember. Behind his eyes, Castiel was eight years old again. The memory pushed into every corner of his mind.

 

_August. 1985._

Castiel could feel the sand crumble beneath his feet and spread between his little toes while he walked slowly down the beach alone, collecting shells. The wind picked up, blowing dark hair across his face. Castiel pushed the strands out his eyes and kept one hand up like a shield, protecting him from the spray of salt water being cast over him by the breeze. He squinted out across the waves while they crashed onto the shoreline. Castiel watched silently as the tide rose and fell, the swell of the sea moving in a relentless cycle. He could hear the distant call of the gulls overhead. His eyes scanned the vast ocean. He didn’t even know what he was hoping to see. It just felt right to be there. He wandered closer to the line marking the divide between the sand and the water.

Castiel looked up and down the beach, but there was nothing. The smell of salt drew him closer still. When he reached the shallows, Castiel felt the cold waves lap over his feet and swirl around his ankles. He rolled up his trouser legs below his knees and waited in the shoals, just watching the roll of water on the horizon. It was getting late, and the warmth of the sun that soaked the bay that afternoon was fading fast. He suppressed a shiver and wrapped his arms tightly around his waist. He thought about calling out. Castiel couldn't explain it, but there was something that pulled him back there, day after day.

He picked up a handful of little pebbles from the wet ground. He rolled them around in his palm a few times to rub off the dry grains of sand, and started to throw them aimlessly one by one into the water. He tried to beat his distance with each stone as they landed with a soft plop and disappeared under the surface. Castiel raised his arm to cast the last one before heading back up the shore, when he saw a small fluttered movement momentarily breach the surface. It wasn’t clear. It may have been the wind or the way his eyes dropped in and out of focus while he searched the waters with narrowed eyes. Castiel waited, keeping his breathing low and shallow. He tried not to make any sudden movements.

He inhaled sharply when he watched one of the pebbles he tossed into the sea skim back towards him and almost land at his feet. He stared at it in amazement before three others came back in quick succession. Castiel looked back up, eyes drifting to the rise of a sandbank just visible through the spray when the waves crashed up against the sides. Castiel started to move carefully along the beach, his eyes now fixed on the far side of the bank where he thought he could see a pale hand resting on the sand. He started to increase his pace when he saw long fingers curling around the curve of the bar. He waded in deeper, no longer caring about the cold of the water rising up his legs and drenching his clothes. He tried to run towards the levee, but his steps were hindered by the pull of the tide, and he was struggling to move forward. Castiel moved through the waves with heavy strides, hypnotized by the movement in the water.

Castiel was about twenty yards away from the small island, when he found it almost impossible to fight against the undercurrent. The wind was blustering around him, catching up the surface of the sea and pitching it hard against the side of his thighs. He stumbled, throwing his arms forward in a futile attempt to prevent himself from falling. His hands pushed effortlessly down through the water and he was dragged under. Castiel spluttered while he managed to regain his balance, spitting out the salty taste and rubbing a damp hand across stinging eyes. He struggled on, his heart beating fast in his chest. A combination of fear and adrenaline.

Castiel knew he was in serious trouble when he was suddenly pulled under again. The curve of the bar was just out of reach. He tried to part-swim, part-wade through the swirling water but his muscles were burning. His limbs felt like lead while he tried to overcome the ebb and flow of the tide. Castiel heard a loud splash and caught another flurry of movement from the corner of his eye. His vision blurred and he dipped under the surface one last time. He could feel the cold biting mercilessly into his body and had to hold his breath until his head pounded, the pressure on his temples almost unbearable. He looked up to see the rolling surface of the sea over his head. The sun looked bright and far away. His eyes started to close when he exhaled his last lung full of air.

There was a sudden and unexpected silence while Castiel drifted with the tide, cold and weariness overcoming all his senses. Without any warning, he felt something grip him from behind. Two smooth arms slipped underneath the pits of his arms and hauled him gracelessly up through the waves with a rush of noise and bubbles. As soon as he breached the surface, Castiel gasped and air flooded into his lungs. His mouth was open, water dripping down his face. He inhaled, fast and deep. He could still feel the strong grip holding him just above the water and dragging him backwards through the waves, watching a white river of foam form in his wake when he was pulled over to the mound of sand.

Castiel came to with a dry cough, water spilling from his mouth. He could feel the rough grains of sand under his fingertips when he dug them in, damp particles sticking to his skin. He sat up quickly, eyes darting over the line of water. His whole body ached and his lungs felt hot and uncomfortable, but his breathing pattern slowly returned to normal. Castiel groaned when he pushed himself up. His hand was clutched against his chest to try and relieve some of the pressure he still felt there. He gasped in surprise when he tried to focus. Along the line of sand he could just see two piercing green eyes, watching him intently. The mouth and nose weren't visible, hidden by the rippling water. Castiel shifted when the eyes quickly disappeared beneath the waves.

_____

** MBRI **

** Research Log **

Research Associate Professor

Dr. C. Milton. MSc (Marine Biology)

** Entry 0.1 **

It has come to the attention of the MBRI that there exists the possibility of video evidence regarding a potentially unclassified species at an undisclosed area off the coast of Maine. The legitimacy of the recording has been substantiated by the witness statement of a local fisherman. Dr. Smith and I have both viewed the tape and concluded the unidentified animal appears to display some humanoid features such as body shape and upper limbs. It moved through the water like a marine mammal and appeared to be approximately six feet in length. Colouring was blue-grey with some flecked markings across the upper portion of the body.

I have subsequently been instructed by the Chief Scientific Officer to lead an investigation to identify the specimen if possible. The aim of the investigation is to make detailed observations of the area, including an underwater exploration and the tagging of a live specimen if possible. This information could then be used to track the migratory routes of this, and any other, individuals of this potentially new species. My team will be leaving in the morning to conduct a preliminary search of the area and to interview any local witnesses. The initial stage will be conducted over a period of four weeks. This may then be extended, depending on the degree of success during this time.

Notes:

Witness wished to remain anonymous. The tape has been tagged and will be reviewed at a later date along with any additional evidence that may be collected by the research team.

 


	2. Genesis

**Summary for the Chapter:**

> Castiel prepares for his investigation, neglecting to mention he may have a secret agenda. He is forced to revisit images from his past once stored away to memory. Castiel encounters some opposition that threatens to stall his project before it has even started, but the pull of the sea is just too strong.

**Genesis**

Castiel shook his head, all those thoughts quickly fading again. He could almost smell the sea spray when his senses returned. It was a very vivid memory. He heard someone come in and spared a glance over one shoulder, smiling in recognition when the resident geophysicist appeared in the doorway. The man was still chewing on his breakfast, so he just waved at Castiel and sat down by the window. He was looking at the gulls while they flew in circles over the harbour. They needed to do some depth studies, and Castiel had no idea how to even turn most of the machines on, let alone actually learn anything from them.

Castiel smiled in response to the wave. Shit, he couldn’t remember his name. He narrowed his eyes and tried to covertly read his I.D. but his glasses were still in his pocket. He had no chance, so pretended to be extraordinarily busy on the computer while they waited for the rest of the team to arrive. Castiel also requested his CSO recruit an underwater photographer and an expert navigator. The biology bit he could handle himself. Marshall was one of the best animal behaviour experts on record and Castiel was relying on him to help track it, if they ever found out what _it_  was. Castiel had his own opinions about that, but he was trying not to let memories cloud his judgement.

He knew deep down he was only trying to convince himself. No one else knew about it anyway, and Castiel liked that. It felt like he had something magical and wonderful in his head and he didn’t really want to share that memory. Secretive, perhaps. Possessive, definitely. That was all his. Those moments spent with the strange boy with green eyes. Castiel had no intention of sharing him.

“Doctor Milton? Castiel Milton?” He heard a pleasant voice from somewhere behind him that shook him from his daydream. Castiel twisted his neck round to put a face to the voice. There was a young man with hazelnut skin and long black hair hanging across his face. He was looking at Castiel with round, chocolate-coloured eyes. Castiel thought he looked about fifteen. He was carrying a very heavy looking camera on a strap draped loosely over one shoulder, and he grinned wide at Castiel when he threw down his backpack at his feet and offered him an outstretched hand.

“Achak. Achak Shaw.” The man added politely. Castiel took his hand and shook it firmly. His gaze was drawn rather to his silver amulet than to his deep eyes. It was bound on a thin band of leather around his neck, and sparkled under the artificial lights of the office like a tiny star. “You wanted a photographer?” He persisted, tilting his head down slightly to try and catch Castiel's eye. He slowly released his hand.

“Sorry. Yes, absolutely… sorry.” Castiel stumbled.

“Just call me Shaw.” Achak grinned. “Most people do.”

“Okay.” Castiel ran one hand through his hair. “Welcome to the team.” Castiel wasted a few minutes on pleasantries before opening the case file he had been studying almost to the point of obsessiveness over the last few hours. He showed his new photographer the stills he captured from the video the day before, and watched Shaw closely while he examined them. Achak made a strange sound in his throat. Castiel thought he might have looked vaguely impressed.

“Well, they look genuine at first glance. What do _you_ think it is?” Shaw asked suddenly, looking directly at Castiel. He wasn’t expecting that so soon. His mouth opened and closed a few times while he was trying to think of something to say, and stammered out the next sentence.

“Oh. Well, I’m not sure. Maybe a new species of mammal. Hard to say, honestly.” Castiel stared at the ground. “There’s really not all that much to go on.” Shaw seemed happy enough with the response. He made a satisfied hum when he gave the photographs back to Castiel and turned his attention to the contents of his backpack. Castiel needed to stop letting his emotions affect him so much. There was absolutely no reason to think it was anything other than something that lost its way in the cold depths. Over-fishing in the open sea off the coast had driven the seals further inland in search of food, and Castiel had seen more harbour porpoises in the bay in the last two years than he ever had before. He hadn’t realized he was tracing his fingers across the image until he saw the shadow of someone standing behind him in the reflection of the computer screen. Castiel pulled his hand away and turned round, leaning back to rest against the counter while he folded both arms across his chest.

“Ready?” Marshall asked. Castiel was so preoccupied with the contents of the folder, he hadn’t even heard his friend come in. Castiel nodded and held his breath. His heart was full of hopeful anticipation, the whole idea of what was ahead pulling at his imagination. He had read almost every academic paper he could find on the theory introduced to him at university. The very real possibility of an aquatic ape. He spent many years trying to reconcile that thought in his head with his own experiences as a child. It wasn’t widely accepted. Potential evidence was rare, and eye witnesses sometimes seemed reluctant to be identified - including him. Castiel smiled brightly and moved away from the desk.

“Absolutely.”

_____

Castiel already left most of the equipment on the side of the dock, and was on his way back up the steps when he spotted Shaw snapping random pictures of some of the preserved specimens lining the hallway. Strange and twisted pale forms. Immortally preserved in big shiny jars.

“Something for the album?” Castiel offered. Shaw turned quickly at the sound of his voice and flashed him another wide grin.

“Something like that.” Shaw replied, placing the camera back on his shoulder and nodding his head towards one of the taller cases. “What’s that?” He asked, with genuine interest. Castiel walked over slowly, smiling to himself. He would pick that one.

“It’s a mermaid.” Castiel said quietly. Shaw’s eyes were scanning the figure behind the glass when Castiel answered. He drew back quickly in surprise. There was something odd about Achak's expression. Castiel shook his head with a cheerless laugh. “Fake, of course.” He clarified, and saw the other man visibly relax. “Just something for the tourists.” Castiel added. He leaned forward and ran his hand down the cold surface of the glass container, silently studying the curves and planes of an artificial grey body shaped into some semblance of a living creature.

“It looks so real.” Shaw commented in a whisper. Castiel suddenly remembered himself and withdrew his hand.

“Hmm.” Castiel mused. “I guess. We had an aquatic ape exhibition a few months ago. Just something I'm quite interested in. It’s very popular on _you tube_ apparently." 

Shaw laughed out loud.

“Do you even know what that is?” 

Castiel frowned, and may have actually been a little offended.

“I’m only thirty-six.”

Shaw’s laughter died on his lips.

“Oh, sorry.” He kicked hard at the floor with the end of one boot, and coughed awkwardly. “You know, my people have many legends about the spirits in the water.” He suddenly announced. Castiel thought he was probably just trying to fill an uncomfortable silence.

“My people?” Castiel echoed, looking confused. Shaw nodded.

“Upstate. My grandmother used to tell me stories.”

“Oh.” Castiel blinked, the realization slowly dawning on him. He forgot there was a reservation in the north. “Like what?” His interest wasn't strictly professional, but he thought he hid it pretty well. Shaw glanced once more at the strange inanimate sculpture behind him before turning back to Castiel. He could have sworn Shaw looked unnerved by it. He leaned in a little closer, but before he could answer, Castiel heard someone yelling his name.

“Where is he?” The voice sounded accusatory and impatient. Castiel flinched when he recognized it.

“Shit.” Castiel whispered under his breath, setting his shoulders straight in a rather pitiful attempt to look taller. One of the side doors was pushed open with so much force, it swung all the way back and banged against the wall. Some of the smaller tanks rattled from the impact. A scrawny and unpleasant looking man in an over-size suit appeared next to them, sneering when his gaze fell on Castiel.

“Milton.” Castiel definitely didn't imagine the curl of the man's lip when he spat out his name, like he was trying to get rid of a mouthful of sulphuric acid he swallowed on accident. He pointed a finger at Castiel like he was about to poke him hard in the chest, but he stopped short and just glared at him instead. His finger hovered in position. “Who authorized this shit?” The man demanded. Castiel bit the inside of his cheek and did his best to hold the gaze.

“CSO.” Castiel mumbled quietly. It was a rather stupid question, but he didn’t bother to point it out. The other man tutted and shook his head.

“I've told you before, this institute isn't a forum for your bloody stupid personal causes. Just because you spend all your spare time pissing about looking for stuff that doesn’t exist, doesn’t mean we all have to pay your damn bills.” Shaw was looking from one man to the other, his mouth open in astonishment. That wasn’t just personally insulting, it was rude. Castiel pressed his fingers into his palms until he could feel the ends digging into the skin. He managed to keep his voice calm.

“I can assure you, _sir_. This is a legitimate scientific investigation.” Castiel hesitated for a moment. “This isn’t about me.” That wasn't entirely true. The man continued to stare at him with disdain, clearly struggling to form an appropriately impolite response. He had nothing, and turned to walk away. Castiel felt his own breath pass slowly between his lips when his shoulders started to relax again.

“It better be... or you'll be finding somewhere else to work.” The man shouted over his shoulder, before storming off up the corridor. The rapid echoes of his footsteps gradually faded away. Castiel heaved in a deep sigh. Both his cheeks were flushed, and Shaw couldn’t be certain if it was from embarrassment or anger. He let out a long, low whistle.

“Who the hell was that?”

Castiel forced a smile, and dropped one hand onto the other man’s shoulder.

“Just a dick. A dick who obviously forgot to take his anti-megalomania pill this morning.”

“No kidding.” Shaw offered, and then he looked at Castiel more softly. His brown eyes were studying the side of Castiel’s face. “Why do you let him talk to you like that?”

Castiel met his gaze.

“I need him. Well, I need to be _here_. Sometimes I have to suck it up and let him get it out of his system. Daddy’s bank account pays my sickeningly large paycheck.” Castiel sighed again. “Long story. Short version - he's always hated me. Call it professional rivalry, if you like. I can fill you in with the details later.” The photographer shrugged and patted Castiel supportively on the back.

“Don’t worry about it. I have a feeling I'd probably rather not know, anyway.”

Castiel was even more determined to prove their existence now. He wanted to shove some indisputable evidence right in his fucking face until he choked on it. More importantly, he longed to fill the empty space in his heart that could only be healed by blue-grey skin and green eyes.

_____

 

_August. 1985._

“Hey! Hey, don’t go!” Castiel called into the wind. He still ached everywhere, but he wanted to see the face of the boy he knew must have saved him from drowning. His chest was still heaving with dry coughs, and the taste of salt water was burning the back of his throat. He spat out another lungful, and twisted his head to scan the surface of the sea. The waves continued to roll up against the bank. Castiel waited patiently, all the while hoping his plea wouldn't go unheeded. The water just looked flat and featureless in every direction. He slumped back in disappointment. 

Castiel ran his small hands through the moist sand, watching the grains spill between his fingers. He was completely soaked and had started to shiver from the cold. He folded his arms across his chest and rubbed vigorously at the skin, wondering how he was going to get back to shore. He heard a splash in the water behind him. Castiel jerked his head around, smile spreading wide when he caught the unmistakable shimmer of a wet, grey body snake through a breaking wave. Almost immediately a small head popped up at the end of the sand bar, effortlessly breaking the surface of the sea. It was him.

The boy's eyes were large and unblinking. The vivid tint to them was piercing against the bland background of his pale skin. His hair was almost white at the roots and seemed to taper away at the ends where the colour almost matched the blue of the sea perfectly. Long hair hung down to his shoulders. It looked like some of it was roughly hewn away at the edges. He had speckled markings across his nose, the tops of both cheeks and some sections of his exposed shoulders. The dots were the same colour as the sand. Castiel watched him while he carefully pulled himself around the ridge of the bank, occasionally dipping the lower half of his face just below the surface. Castiel reached out a trembling hand towards him when he slowly drifted closer with the tide. He rubbed his fingers together in the way people did when they were trying to coax an animal to come to them. The boy frowned. Castiel realized he hadn’t actually got anything to give him, and worried his lip. The boy didn’t look very dangerous, but appearances could be deceptive.

He was closer now, maybe a metre at best. Castiel suddenly wondered what it would be like to touch him. His skin looked like it would be soft and silky under his fingers. He noticed the part of his body that was out of the water appeared to be almost completely hairless. He studied his face.

“Come on, come here.” Castiel enticed him with a gentle voice, still making subtle gestures with the hand that was reaching forward. The boy cocked his head to one side and finally blinked, just once. Castiel was almost touching him, when he suddenly pushed his body up and out of the water to get a better reach on the dive. He disappeared in a flurry of white foam. Castiel scrunched up his nose and let out a breath. He must have scared him off. He was chastising himself in his head when the boy reappeared just as swiftly and pulled the top half of his body up to rest on the edge of the sand. He reached out a pale hand with unnaturally long fingers and deposited a large pink shell in front of Castiel’s knees. It was lovely, a flawless swirl of defined edges. The inside shimmered and glistened when the light reflected off the small droplets of sea water caught inside it. It was a gift, a very beautiful gift. Castiel picked it up and moved it around in his palm while he examined it. When his eyes flicked back up, the boy had gone. The surface of the water was still again.

“Thank you!” Castiel called out. His voice was lost on the breeze.

_____

 


	3. Memories

**Summary for the Chapter:**

> Castiel heads out on his first field trip to the area where the initial sighting took place. There appears to be something in the deeper waters, but physical evidence remains inconclusive. He hears a familiar call that pulls at fragmented memories from his childhood. Making Castiel realize he has heard that sound before.

**Memories**

Castiel scanned the skies. Heavy grey clouds were rushing over the harbour. There was going to be a downpour, and they hadn’t even loaded all the equipment on the boat yet. Castiel jumped up onto the deck and gestured for Marshall to hand up the cases and the sonar box. After a few minutes, most of the technical gear was stowed away safely in the main cabin. Castiel couldn’t resist a few furtive glances over the bay like he was searching for something. He hadn’t realized Shaw was watching him from the first floor, guessing he had enough time to take a few last shots from a higher vantage point. It wasn’t often Achak had the opportunity to be more creative with his art. That was the point though, he hadn’t been hired to be imaginative. He was there to document scientific evidence and nothing more. His thoughts started to drift while he silently studied Castiel from the window. There was something that made him question his motivation. He saw the way Castiel looked at the artificial form of the mermaid earlier. Shaw was starting to feel Castiel was more personally involved with the project than he first appeared to be. He was definitely guarded when anyone asked him his opinion on the photographs. Shaw had noticed that already, and made a note to try and coax some more information out of him later when they were alone.

Achak Shaw also had his own story to tell. Growing up with his grandmother on Peter Dana Point, listening to her tales of Ne Hwas, and the spirits of the water. He had always been fascinated by them. He knew Dr. Milton had that same look in his eyes when he talked about the mermaid. There was definitely something about him that Shaw wanted to know more about. Maybe he had finally found someone who could help him learn the truth.

Castiel looked like he was almost ready to leave. Smith appeared next to him on the dock while Shaw was busy daydreaming, and he couldn’t help but smile when he noticed the other man had covered almost his entire body with a bright yellow slicker. Shaw didn’t like him. There was something dark about Smith, like he was hiding behind a mask. Achak had always been good at reading people. He looked ridiculous, for one. It hadn't even started to rain yet. He liked Milton though. He was genuine, and there was a lot of sincerity reflected in those blue eyes. Shaw slung the camera over one shoulder and pushed his dark hair out of the way until it fell freely down his back. He took one last glance behind him and hurried down to reach the boat before they left without him.

Castiel greeted him warmly when he hopped up onto the deck, holding Shaw by the arm to steady him. The sea was looking a little rough, but it was navigable and the boat was only swaying slightly on the surface of the rolling water. Castiel pulled at the rope tied around a weathered pole on the waterside. Marshall helped him unwrap it, and the little craft started to drift away from the edge. He launched himself forward and landed on the floor of the boat with a graceless thud.

“Smooth.” Castiel laughed. 

“You’re doing it next time.” Smith replied. Castiel was silenced immediately by the thought of having to propel himself onto a moving boat. Shaw patted him on the back again.

_____

They cut the engine about two miles off the coast. Shaw was setting up the underwater equipment and making sure there would be no delay on the live feed. He was fiddling with the wiring when he heard Marshall calling Castiel from inside the cabin. He already matched up the co-ordinates, and decided it was as good a place as any to start an initial survey. The clouds overhead were still heavy with water, but Castiel wasn't going to be deterred by a little bit of rain. He had been trying to ignore the fluttering inside his stomach constantly distracting him all morning. He pushed the image of the boy from his mind. Again.

Shaw lowered the camera into the water, threading a long length of black cable through damp hands until he was sure the machine was low enough to capture anything moving through the deeper waters. Castiel was peering over the side of the railing. The sea was murky and a deeper green than usual. He didn’t have much hope of seeing anything under the surface at all, and his heart sank.

He knew sightings were random and unpredictable, and getting something on film was even more unlikely. He hadn’t really planned what they were going to do if they actually did find something. Castiel couldn’t bring himself to cage one like an animal, or threaten their survival as a species. The concept made him feel sick. He spared a glance at his friend. He knew Marshall probably wouldn't be quite so sensitive. Castiel shook his head and continued to stare down into the waves. He could worry about that later. Maybe he should have approached the whole thing more strategically. It was too late now, Marshall had seen that video, and had been desperate for some sort of recognition for years. Castiel was beginning to regret involving anyone else at all. His stomach flipped over when he realized how careless and impulsive he'd been at initiating field work so quickly without even considering the consequences. He was so excited by the film, he'd abandoned all logical thought. _Shit._

They stayed in the same spot for most of the morning. Shaw was sitting down. He had the cable looped around one hand, both feet propped up on the side of the deck. His eyes kept fluttering shut like he was only moments away from sleep. The monitor was making regular clicks and beeps, so Castiel kept checking the screen for any signs of movement. The rain had been and gone. The water was clearer than it had been earlier in the day, but it was still dull and grey. The sea breeze much colder than he anticipated. Castiel was staring aimlessly across the far line of the horizon, when he saw Shaw suddenly drop his legs from the side and jump up. He flung the top half of his body tight against the upper railing, excitedly watching the water a few feet from the edge. Castiel was by his side in seconds.

“There!” Shaw yelled, grabbing for Castiel’s sleeve without taking his gaze off the sea. Castiel felt his heart skip a beat. There were a few fading ripples and a small wake of foam on the surface.

“What? What did you see?” Castiel asked breathlessly. Shaw was still scanning the waters with frantic eyes.

“I saw something, something big. I don’t know what it was, but it was quick.”

Both men were leaning over the railing. Castiel knew he was breathing heavily but he couldn’t seem to control it. They both watched the waves silently for a few moments. Castiel thought he saw something dark swim under the boat and hurried to the other side to see if anything would emerge from underneath the vessel. He heard Shaw open the cabin door but he didn’t turn round. He felt almost hypnotized by the blue of the water. Shaw was checking the monitor, but there was nothing. The sonar picked up a couple of strange anomalies that looked like large objects moving fairly fast over the sea bed, but nothing conclusive.

“Anything?” Castiel called over his shoulder, but his gaze quickly returned to the shifting tide. There was no reply. Shaw was too focused on the screens in front of him. Castiel could feel a few fresh spots of rain falling on his face while he moved his head to search the rise of the ocean in every direction. The water was trickling down and dripping into his eyes, making it very difficult to see. He was just about to dip into the cabin and out of the rain, when he heard a shrill call in the distance. He thought at first it might have been a gull, but it seemed drawn out and pitched differently. Castiel cocked his head to one side and listened. It came again. There were no words, but there was something hauntingly familiar about it, and Castiel searched his mind for a memory that had been forgotten.

_____

 

_August. 1985._

“Don’t be stupid, Castiel. People don’t live in water. Where on earth would you get such a ridiculous idea?” His mother responded blankly. She didn't even look up from her book. Castiel was standing in the open doorway with sea water dripping from his hair. He turned away and ran all the way up to one of the bedrooms, tears of humiliation and hurt stinging at the corners of his eyes. He threw himself down on the bed and cried until he fell asleep.

Early next morning, Castiel crept out of the beach house with a crust of bread stuffed into the pocket of his shorts. He left a hand scrawled note on the kitchen table just in case one of them actually wondered where he was. He was used to entertaining himself. They came to the same place every year for most of the summer. Father said it was so he could work in peace, but Castiel couldn’t remember ever seeing him do much of anything for weeks at a time. He was always alone. Sometimes he liked it, and sometimes he didn’t. He liked being with the boy from the water. He liked that very much.

He had to be more careful this time, Castiel thought, while he meandered down the cool sand. The tide had gone back out and left small pools of water in dips along the coastline. Castiel would sometimes inspect them for starfish and new shells, but often he would just dig his toes into the wet sand at the bottom and watch the edges of his feet disappear. He knew he had been very lucky the day before. He could easily have drowned, and no one would ever have known what happened to him. His small body would have been carried out to sea in minutes. He shuddered at the thought. Castiel wasn’t sure whether the strange boy in the sea lived close by. There was no guarantee he would be there to save him again.

Castiel waited at the edge of the ocean and silently watched the waves as they pitched back and forth across the sand. It was definitely calmer than the day before, but the memory of being dragged down into the cold dark water was still uppermost in his mind, and he had no desire to repeat the experience. He kept close to the edge of the shoreline and made no attempt to go into the sea. He sat down on the damp sand and took the bread out his pocket. Castiel started to tear off small pieces and set them out next to him on the sand. He threw one in and watched it sink slowly under the surface. There was no movement in the water and he felt more than a little disappointed. It was stupid to expect anyone to still be there. He probably didn’t eat bread, anyway. Castiel thought afterwards it was an insane idea. If the boy did actually live in the sea, he probably ate fish or snails, or something. Castiel was pondering the theory distractedly, when his senses were suddenly alerted to a strange sound in the distance that seemed to resonate through the water. It sounded like a combination of clicks and whistles, with some sustained higher notes that seemed to carry effortlessly on the air. He squinted across the sea, fighting the bright glare of the early dawn. Castiel couldn’t quite locate the source, or the direction of the call. He couldn't see anything except the line of a far horizon. He picked up another piece of bread and squashed it between his fingers before throwing it into the depths. There was a brief moment of silence before the call came again. Castiel was almost certain it was getting closer. He listened intently. If there were any words to it, he couldn't understand them, but the intonations in the sounds made it clear there was a definite purpose there. It was pleasant and soothing. Castiel knew he couldn’t hope to replicate those sounds, so he just listened harder. The soft tones washed over him while he sat at the edge of the water. His toes nudged at the line of stones pushed in by the tide and deposited at his feet as a reminder of its timeless constancy.

Castiel hadn’t even noticed how the water was swirling in small circles a few metres out from shore. There was a sudden and unexpected rift in the waves where they were breaking in the shallows. Castiel gathered up the remainder of the bread and threw it all in at once in the place where he saw the ripples spreading out from a single point. He smiled wide when he saw a pale grey hand slide through the surface of the water and pull most of the pieces down under the waves.

_____ 

** MBRI **

** Research Log **

Research Associate Professor

Dr. C. Milton. MSc (Marine Biology)

**Entry 0.2**

I have assembled an initial team of five members including a geophysicist, an underwater photographer, and a navigator. Marshall Smith and I will be leading the investigation. Our intention is to make a basic map of the area with details of any potential sightings. We will initiate a deep bed scan to assess the nature of the terrain and establish whether the area where the sighting occurred has enough resources to sustain a population of these creatures.

Main concerns are that the area is extensive and time is limited. The main harbour is reasonably secluded and one of the main priorities is to ensure this investigation remains unpublished locally. We will need an opportunity to study any potential living specimens and take relevant tissue and blood samples, if possible. I am reluctant to publish any findings until we are certain there is sufficient scientific evidence to support our hypothesis.

Notes:

The team photographer has verified original footage doesn't seem to have been tampered with prior to submission. The stills appear to be genuine. He is in the process of collecting more relevant photographic evidence from other sources to ascertain the validity of previously documented evidence. He will be submitting a report of his findings in due course.


	4. Chance

**Summary for the Chapter:**

> Castiel is fascinated by an unusual sonar reading in the deeper water. Memories start to return the more time he spends in the place where he once encountered the mysterious boy from the water he longs to see again. The desire to be with him one last time causes Castiel to make an impulsive decision that almost costs him his life.

**Chance**

Castiel could feel his heart beating fast under his shirt, all his senses searching for the source of the cry. It didn’t sound entirely human, but he didn’t think it was an animal either. Castiel held his breath and let the rain fall on his face while he waited. The memory of that ethereal voice started to filter through his mind, hoping beyond hope it was what he thought it was. How long he had waited to hear that sound again. So many years had been spent looking for something he thought he'd lost. _He_ had been lost, all that time. Castiel pushed all those emotions down, deep inside his heart. He suddenly felt very ashamed. He hadn't meant to leave the boy. The thought faded away when he heard someone calling his name.

“Dr. Milton? Castiel?” Shaw called, through a harsh wind that started to pick up. It blustered against the small craft while it bobbed up and down on the rising waves. Shaw called again. Castiel reluctantly pushed himself away from the side of the railing but his eyes never left the water.

“Sorry, yes. What is it?” Castiel replied. His voice sounded distant and remote.

“Come here, I think you might want to look at this.” Castiel hurried into the cabin and let his gaze fall on the small monitor. He followed the line of Shaw’s finger where he was pointing a shaky hand at a blip on the signal. The vivid light shone out brightly in the dim room. As Castiel watched it cross the screen, he felt a gasp catch in his throat.

“What the hell is that?” He managed to stutter after a few seconds. Shaw shrugged, but his eyes were shining.

“It sure is something.” Achak offered quickly. He started to press a few buttons, and the image quickly came into focus. Castiel had no idea what he was doing. “At first, I thought it was a dolphin but it looks too wide at the tail, and it sort of glides through the water. Dolphins don’t move like that.” Shaw continued. “They swim in a specific way, and there’s usually more than one.” Shaw was watching the excitement pass over Castiel’s features while he stared more intently at the reading. “Whatever it is - it’s alone.”

“How big?” Castiel asked, resting his chin on his hand like he was trying to stop his mouth from falling open.

“I’d say between five and seven feet, give or take. Difficult to tell. I’m just gonna check the camera.” Shaw added, turning to the other side of the counter to view another monitor. Castiel was transfixed by the sonar screen while he watched the signal with wide eyes.

“Hey. Hey, it just turned.” Castiel grabbed blindly behind him, trying to feel for the sleeve of his companion’s jacket but not willing to pull his gaze away. Shaw let out a small noise of frustration at trying to view so many different things at once and Castiel felt some movement beside him. Shaw played back the recording.

“Curious.” He played it back a second time. Shaw suddenly frowned while he watched the dot of light. He almost pushed Castiel out the way when he pressed his hand against his back. “Shit, go. Go and look over the side, it’s coming up.” Castiel almost tripped over the thick cables in his haste to get back outside. He felt like he couldn’t breathe, slipping over the wet planks before steadying himself on the rail. Castiel reached the edge and peered without blinking into the blue water until his eyes started to sting with the effort. His features were contorted with a strange combination of hope and desperation. There was nothing. He turned his head briefly to shout some creative abuse at Shaw for talking shit, when he heard a splash and flicked his head sharply back round. Then he stopped breathing altogether.

Castiel saw a blur of movement and the rise of a blue-grey tail fin breach the calm, then dip back down almost as quickly. Castiel curled his fingers around the bar until his knuckles turned white. A few fragile bubbles of foam littered the surface for a moment where the water got churned up. They slowly burst and disappeared like they were never there. All that was left were a few dying ripples spreading out across the top of the water.

Castiel finally took a breath. He pulled away from the rail and propelled himself up the ladder at the side of the cabin in seconds. He was standing on the very top of the boat, his feet apart, swaying with the motion of the tide for fear of being cast over the side. The rain was starting to fall harder, slanting across his vision and making it difficult to see. He put up one hand to shield his eyes from the pelting water, but it didn’t help. He scanned the ocean once more with concern. Heart now beating so fast, the noise of the wind was almost lost to him. Castiel focused on the area where he last saw the disturbance in the waves and almost called out. It wouldn’t have done any good. He knew that with all his logical senses, but he was starting to become desperate. He needed to know for sure, not daring to hope it could be the one thing he searched for most of his life. The reason he had studied marine biology. His reason for everything. There must have been more of them. Even if he could find just one, it might help him to find the boy he lost all those years ago. The thought drenched his mind and clouded his judgement. Castiel hesitated, just for a moment. Then he held his breath and closed his eyes before throwing himself over the side of the boat and into the cold water.

Castiel plummeted downwards, the impact disorienting him for a few seconds until he thrashed his arms and managed to drive his body upwards when he exhaled a deep breath. He reached the surface and turned small circles in the water, the weight of his soaked clothing becoming an unbearable burden while he struggled to stay afloat. Through the driving rain he could just make out the horrified expression on Shaw’s face when Castiel saw him lurch to the side of the deck and scramble for the life preserver.

“What the fuck are you doing?” Shaw yelled in panic. When he didn't get a reply, he unhooked it quickly and secured one end of the throw rope to the peg. He stepped back and lifted his arm to get a better distance. Shaw launched it over the side, just before Castiel dipped under the surface again and heard a faint voice drift through the air. “Man overboard!” Shaw's voice was filled with alarm, his gaze switching between Castiel and another crew member who was busy in the engine room. Castiel wasn’t even looking at them when the other man appeared next to Shaw at the edge of the deck. Castiel didn’t even attempt to reach for the rope drifting uselessly with the swelling tide.

“Milton!” The other man yelled down. “Grab it, grab the rope!” He turned to Shaw with a deep frown and waved his hands in disbelief. “What the hell is he doing? Why doesn’t he just make a grab for it?” Both men stared over the side where Castiel was moving with the water. He was starting to tire, and his arms felt heavy. He was kicking his legs just below the surface to try and stop himself from being pulled back down. The men continued to shout his name and encourage Castiel to save himself, but he wasn’t listening. He was running his fingers through the cold water surrounding him and peering down into the dark depths like he expected to see something. Minutes passed, and the men who were still on the boat were getting frantic. The fear in their voices was clearer now. Time was running out, and they knew it.

Castiel closed his eyes. He was wrong, _so wrong_. He thought, awareness starting to fade. He had believed in his own eyes, and his own heart and both had failed him. Just as he prepared to give one last fight to reach for the rope, he heard that call again. It was coming from underneath him. Castiel suddenly stopped moving. His head disappeared under the water and covered his mouth. The pressure was terrible. He opened his eyes and tried to blink the sting of salt away. He was going to lose consciousness. This was it.

The last thing Castiel remembered was a rush of noise surging up from below his feet and a stream of bubbles pushing up all around him. He thought for a brief moment he felt something grab at his legs and thrust him upwards. Castiel imagined that was what it must be like to die. Seeing things in your mind that aren’t there. Holding on to snatches of past memories that mean something.

Green eyes.

_____

The two men managed to pull Castiel in, and haul his almost lifeless body onto the deck. Shaw tipped Castiel over onto his back, his head thudding heavily against the wooden floor when Shaw pulled the rope away. It had somehow become twisted around his body. Shaw roughly opened Castiel's jacket and placed his ear against his chest. He felt his damp wrist for signs of a pulse.

“Fuck. Fuck, he’s not breathing.” Shaw pressed his palms together and pushed them hard against the dip in Castiel’s chest. His mouth was moving silently around numbers he was counting in his head. “Come on.” Achak muttered under his breath, closing his mouth over Castiel’s to force some air into his lungs. Three times, four. Castiel suddenly coughed and a stream of water spewed gracelessly from his lips and dripped down the side of his face. Shaw shook him by the shoulders. With another gasp, more fluid came spilling out and Castiel spluttered back to life. His eyes were still closed, but Shaw could see the faint rise and fall of his chest.

He was alive. Just.

 

_July. 1994._

The beach house didn’t really seem so exciting anymore. The paint was starting to peel on the wall facing the sea, and the spare bed had become too small and uncomfortable years ago. When it rained, water dripped through the gap in the window frame. Castiel used to think it was endearing and reminded him of home. Now it was just irritating, and somebody should really fix it. It was only a matter of time before he would be able to save up enough money to make his own way in the world. This would be the last time he would come here. Castiel felt it in his heart, and couldn’t find it in him to care. He didn't even remember the last conversation with his mother where she even bothered to make eye contact with him, and his father was locked in his study behind the vast oak door Castiel wasn't allowed behind. He didn’t care, it was probably full of boring stuff anyway.

He would miss the ocean though. It was his place of peace. Every year Castiel returned to the shore, watching, hoping. He had never seen _him_ again, though. Not since the long lonely summer when they first met. The beautiful boy from the water. Castiel had missed him so much. Almost ten years. Years that had rushed by unchecked. He still thought about that boy every single day. Castiel could feel his eyes filling up.

One last time. He swore to himself that day while he stood in front of the crumbling house with the sun casting shadows behind him and the cool sea breeze playing with his hair. One last time before Castiel would leave Winter Harbour forever and never return. He could take that memory with him wherever he went, no matter what. The memory of those deep green eyes would stay in his heart forever.

Sometimes memories are not enough.

Castiel sprinted all the way down the rise of the sand. To his surprise, he felt hot tears fall effortlessly from his eyes. He didn’t even know why, or where they'd come from, but they stained his cheeks and left a delicate trail of salt on his skin. He stood rigid when he reached the edge of the water and let his arms fall useless at his sides. Castiel shouted until his lungs were empty and his throat ached. He wiped a hand across his face and slumped to his knees on the sharp pebbles, flinching at the sting.

Castiel didn’t even know why he was crying. No one would have believed him anyway, and he would be damned if he would share that boy, or let anyone hurt him. Even those who were supposed to love him just laughed at him for his stories, so he stopped telling them. Castiel didn’t care. _He_ knew the truth about the people in the water. It was his secret. That was all that mattered, and if he had to spend a lifetime trying to find him again, then that was alright.

Castiel didn’t have to wait though, not that time.

He was seventeen years old and destined to become one of the most prominent marine biologists in the state, and yet there he was. Sobbing on his knees in front of a featureless ocean with his heart aching for someone he didn’t even know anything about. Not yet.

_____


	5. Kiss

**Summary for the Chapter:**

> Castiel is pulled from the water and rushed to the local hospital. While he lays unconscious and fighting for life, his subconscious relives a precious moment he once shared with the mysterious boy from the sea. That boy has now grown into a breathtaking young man and Castiel still finds himself inexplicably drawn to him.

**Kiss**

Click.

Flickering lights behind his eyes. Muffled noises calling his senses, willing him to come back. Castiel didn’t want to come back, not right now. He was on the beach. Images flashed and faded before he could even register what they were. He was seventeen years old again, waiting patiently at the edge of the water for the boy with green eyes.

Everything was dark and cold. Everything except that pin-point of light beckoning him and leading him gently down to the water. Castiel could hear the rush of the sea as it moved up and down the shore and formed lines of foam at his feet. He could feel the cold, wet sand clinging round his toes when he pushed them into the soft surface. The sky was blue. The grey shadow of a gull soared overhead, wings outstretched as it moved effortlessly through the air. There was a fluttered movement in the water. _He_ was coming.

Click.

A regulated push of air, when the machine moved up and down. Someone was calling him.

It was so dark. _Why was it so dark?_

There were no clouds. Castiel could hear the faint whisper of voices in his head, but he couldn’t see anyone. He looked up and down the shoreline with frantic eyes. The voices eventually faded into the distance. There was a constant wash of noise in the background. He wanted it to go away. He was happy. The boy was coming back for him, and he was happy.

_____

Castiel was lying motionless in a hospital bed in Trenton. He had never regained consciousness after being pulled out of the ocean by the two men who were now sitting outside in the waiting room. In his mind, Castiel was reliving a precious memory. His fingers twitched on the bed and the bright line on the monitor peaked for a moment before it was calm again.

Click.

_____

_July. 1994._

Castiel couldn’t be sure how long he waited at the edge of the sea. The water was starting to roll in and caress his knees with gentle waves. The churning foam soaked into the material of his jeans while it crept ever closer like a silent shadow. Castiel looked up and wiped his hand across his eyes and the bottom of his nose. He never cried. There were so many reasons in his life that might have allowed the tears to fall, but none had ever come close to affecting him as much as the thought of never seeing the boy in the water again. Castiel vowed to himself he wouldn’t come back here next year. Too many painful memories and lonely days had made his childhood holiday home into nothing more than a place that now weighed heavily on his heart.

Castiel narrowed his eyes and glanced out across the ocean. They were both a little swollen, edged with a pale red line. He shifted slightly on the pebbles in discomfort. The sting had worn off almost immediately, but his legs still ached from the exertion of sprinting down the shoreline and the cold, relentless bite of the water. He wouldn’t go back to the house, not yet. He would wait just one more time. The last time.

Before the thought even left him, Castiel picked up a handful of smooth pebbles and started to throw them into the water. A routine he had practiced well over many years of summer visits to the harbour. It had worked once before, but that seemed like a lifetime ago. Castiel deliberately ignored the treacherous voice in his head reminding him of the last nine summers without him. He had sat by the water every day for four weeks, with nothing but the call of the gulls and the odd wayward crab to keep him company. He wasn’t very hopeful as he cast the last pebble out a little further than the rest and sighed when he watched the small stone disappear under the surface of the waves. Castiel didn’t know why he was so fascinated by a boy he had only seen once, so many years ago. It was like he had called out to him somehow. Castiel would never forget the look in those eyes that had captivated him so completely.

As he brushed down the salt slowly drying on his clothes, Castiel made an effort to stand and shake the cold ache from his limbs before he prepared to go back to the house. He was almost fully up when Castiel felt his heart stutter and then pound behind his ribs. He could see a familiar tail fin break the water a few metres ahead of him. He heard himself make a small gasp of excited disbelief in his throat, breath coming out in rapid gasps. Castiel watched in awe at the way it moved gracefully through the waves, gradually getting closer towards him. His eyes were fixed, unblinking when he saw the smooth body breach the surface and the mess of damp hair surrounding a pale face. Castiel smiled. He couldn’t stop himself. It grew wider as the boy approached, but it wasn’t a boy anymore. Castiel gasped again when he took in the sight. He had grown a lot since their last meeting. His hair was longer, and his shoulders were much broader. His chest had filled out and Castiel could just see the lines of tight muscle where they twitched under his skin when he moved. His eyes were the same though. Deep and round, and everything Castiel remembered them to be. Pretty. Intoxicating. Wonderful. He had run out of adjectives in his head by the time the young man was almost close enough to touch. He seemed to hesitate while he drifted up and down with the tide. For a terrible moment, Castiel wondered if he would remember him. The young man stared at Castiel's mouth where his smile radiated the joy he felt inside at seeing him again. The boy tilted his head slightly while he studied him. He seemed unsure of what that gesture implied. After a brief moment of doubt, his top lip began to twitch at one corner. The side of his mouth started to curve into an arc and Castiel realized he was trying to copy his expression. It only made him smile more.

There was something else there now, though. Not just the warmth of his presence Castiel had felt so intensely as a boy. There was something about the boy in the water that stirred deep inside Castiel and made him feel like fire was flowing through his veins. Castiel wanted to reach out and touch him.

The young man started to respond to the smile. He edged closer until Castiel could see himself reflected in the shine of the green eyes that were now searching his face. He seemed to be studying every line and curve. He knew he had changed too. Castiel held his breath while the other man pushed his body through the shallows and propped himself up on the shoreline. He was resting on his elbows. They dug into the wet sand while he stared up at Castiel with his chin balanced in both hands. The lower half of his body was still under the water, but Castiel could see the shape of a round curve where his back dipped down into a long thick tail that splayed out at the base into two branches that were rounded at the ends. He blinked and pulled his gaze away. Castiel crouched down again and just looked at him. All the ache and cold didn’t seem to matter anymore. Castiel reached out one hand slowly, spreading his fingers wide and inching their tips, little by little, towards his cheek. The man jerked his head back and twitched his tail in small nervous circles in the water, stirring up the sand and pebbles when he moved. Castiel felt a sharp sting of disappointment when he recoiled. Castiel leaned in slightly and tried again.

“Hey, shh... shh.” He coaxed, tentatively stretching his hand forward again. “You grew up.” Castiel offered breathlessly. “It’s me, Castiel. Do you remember?” He whispered, as calmly as he could over the tightness in his throat when he tried to speak. He was terrified he might scare him away again, and that would be the end of it. The end of everything. Castiel could never hope to make the young man understand how long he'd waited for him. “Don’t be scared.” He added softly, shaking his head and letting out a small pained laugh that had no amusement in it. “You can’t understand me, I know.” His voice was catching on the breeze while the wind began to pick up. The water on the man’s hair was starting to evaporate quickly, and Castiel could see faint traces of dried salt at the ends, a testament to all his time spent in the deep ocean. Castiel could feel his heart beating faster when he closed the distance between them, and the man remained almost too still while Castiel’s fingertips brushed across the side of his face. He didn’t know why, but Castiel thought he would be cold to the touch. There was an unexpected warmth spreading out from his skin, and Castiel exhaled a rush of air at the sensation of the contact. “I really missed you.” Castiel said gently. The young man just continued to stare at him with wide, green eyes. There was a flicker of recognition behind them, and Castiel could have stayed in that moment forever. The coast was deserted, and there was a chill edge to the air that made him shiver. The man pulled himself up the sand and mirrored the gesture, long fingers tracing the line of Castiel’s jaw. He seemed surprised at the hard texture of the dark stubble that tickled the skin of his fingers when he caressed his face. He ran them along and up until the very ends were hovering over Castiel's lips. He blinked when Castiel breathed hard against them, and he knew the other man could feel the heat emanating from deep inside his chest. Castiel hardly dared to breathe at all when he felt the man drag a single fingertip along his mouth. He gasped when he dipped it in between his lips to feel the wetness gathering on the end of his tongue. He looked fascinated by it, and Castiel knew he was blushing. Castiel swallowed loudly, and the man pulled his finger away. His expression melted gently into a worried frown, like he feared he might have done something wrong. Castiel quickly reached for him and wrapped his fingers carefully around his wrist, pulling one hand back towards his face. “It’s okay.” He smiled. “It’s okay, you can touch me.”

Castiel knew the man didn’t understand what he was saying, but he hoped the soft lilt in his voice and the intimacy of the gesture would help him to realize he really didn’t mind. He wanted it. He wanted to feel the slow drag of long, flexing fingers covering his mouth. The frown disappeared almost immediately, and Castiel thought he saw his lip attempt to curl up again at one corner. He slackened the grip around his wrist, just enough for him to be able to move his hand more freely. The man seemed to understand it was alright to touch, and continued to explore Castiel’s flushed face with his fingers. His gaze never faltered.

Castiel coaxed his hand down slowly onto his chest, and held the man’s smooth palm against his shirt in the space that covered his heart. He rested it there for a moment. The boy's hand was trembling, and he made a small noise that could have been a word, but the meaning was lost to Castiel and he held him steady while he willed the man from the water to feel his heartbeat against his skin. He wanted him to know they were the same. They just came from different worlds.

“Castiel, remember?” He repeated, and pushed the man’s hand harder against his chest. “Castiel.” 

The man nodded his head like he understood, threading his fingers through Castiel’s. He pulled both their hands back towards his body and placed it over his own skin. Castiel could feel a heart beating in steady rhythm, just like his own. He pulled him closer to the edge of the water, their fingers still laced together, and made a strange sound that reverberated through his chest and into a shrill whistle followed by a series of stilted clicks. Castiel could feel the vibration under his palm where it was resting on his bare skin.

Castiel felt himself get tugged in a little more, his other hand instinctively pushing down through the water to save himself from falling into the shallow waves breaking on the sand beneath him. He was dangerously close to being pulled under. The depth of those eyes seemed to hypnotize him when he leaned forward. Castiel could never explain exactly what it was that came over him when he moved in closer. He suddenly felt consumed with a desperate longing that only intensified when he saw the black irises spread wide across the green of those eyes. Castiel dipped his head to cover the man's mouth with his own and placed a delicate kiss to his lips.

_____


	6. Senseless

**Summary for the Chapter:**

> Castiel is haunted by a disturbing nightmare while he recovers in hospital. Fractured memories playing in his mind. He wakes up to the realization his dream could be a warning something terrible is about to happen. The project agenda seems to have shifted focus in his absence, and plans to capture a live specimen are set in motion.

**Senseless**

Castiel could almost feel the soft press of that first gentle kiss while he lay asleep and dreaming. The memory was so fresh and beautiful, he wanted to stay there always with their mouths fastened together. He had been unconscious for two days. On the evening of the second day, Castiel was able to breathe on his own, and the doctor assured it would probably only be a matter of hours before his heart rate returned to normal.

Back at the institute, Smith had wasted no time in making plans to lead his own field investigation. He did have a genuine interest in locating a specimen for his own purposes, but said nothing of his true intentions to his friend. Marshall thought Castiel was too sentimental. There might not even be any truth to the rumours that soon started to circulate along the many white corridors of the building. Marshall never possessed the same conviction Castiel had. Their theories were not always well received, and some of those in higher positions had practically laughed in Castiel’s face when he put forward his own take on the aquatic ape hypothesis. He regretted the decision to share almost as soon as he finished his formal presentation on the possibilities of such a creature existing. The hope something like that could endure outside of myth and legend, let alone off the coast of Maine, was conceptually challenging at best. Every day that followed his fateful admission, made Castiel wish he had kept it a secret after all.

His motivation was actually very simple. Castiel desperately wanted to find that boy who had grown into an exceptional form of a man. Castiel could still see his face when he closed his eyes. Lying alone in his bed, night after night. Castiel remembered how those lips had felt pushed against his own. Nights evolved into weeks, and then into years. He often imagined the strong flex of those muscles under the grey skin, the smooth glide of his perfect body soaring through the breaking waves and diving into the deep ocean. He was so free.

Castiel wanted him to stay that way, but sometimes a darker part of him wanted to take that beautiful creature from the depths of the sea and keep him forever - possess him. Castiel stirred in his sleep. The regulated clicks of the machine were muffled and distant. There was a constant hum of background noise that permeated hazy thoughts. It kept pulling him back, while he tried to surrender to the feeling of peace sweeping over him whenever he remembered the boy. Castiel just wanted to go to him.

Castiel’s eyes fluttered under his lids while he watched fractured images from a distant memory flicker in and out of focus. The man from the water was lying in the shallows, head resting on his hands. He watched Castiel roll up the material of his trousers to his knees, and dip the ends of his toes into the foam at the edge of the water. Castiel tipped his head back and laughed when the man lifted up his powerful tail and twisted it in small circles behind him. Castiel thought he looked happy. He didn’t seem to smile much, but he could always see the delight shine through when they were together. The green of his eyes almost pulled Castiel in. He felt like he could drown in them.

The sky grew darker. Heavy grey rain clouds moved quickly across the sky. This wasn't a memory now. It was a flash of panic and fear when the young man gracefully descended back under the waves and swam just out of reach. He was looking at Castiel over his shoulder through half-closed eyes. He wanted his friend to follow him. The man brought his tail down with a playful flick, and a small spray of salt sprinkled Castiel’s face. He blinked.

His boy was swimming away. Castiel could feel the smile fade when he realized he had to let him go. He tried to call to him, but his voice was taken by the breeze. A streak of lightning crashed across the sky. Everything was fading. Castiel opened his mouth to call him back…

Castiel suddenly cried out and sat up with a jolt. He was breathing heavily, pulling mindlessly at the tubes and wires attached to his body. He was drenched with sweat and his heart was racing. He looked wildly around the small hospital room with wide eyes. Castiel had no idea what just happened or where he was, but the terrible image from the dream was playing behind his eyes. He was panting when he threw back the covers and tried to climb from the bed. He was still dizzy, staggering slightly when his feet touched the floor. He saw a blue blur pass by his side. Someone was holding him up. He could feel a gentle pressure under both arms.

“What are you doing? Get back into bed.” Castiel heard a voice at his side. He frowned, and tried to focus. A small woman in uniform was tugging at his elbow. “Sir, please.” She tried again. Her tone was softer now, more of a request than an instruction. Castiel moved unsteadily and took a couple of paces back until he felt the edge of the bed pressing against the dip in his knees. He was still reluctant to lay back down.

“No.” He struggled to free his arm from her grip. “I can’t... I need to get back.” Castiel slurred. He felt disoriented and weak, his throat unnaturally dry. “Something’s wrong… I need to - ” The last words were lost when he swayed, and then fell onto the bed. The nurse lifted up his legs and covered him with a sheet. He was asleep again before she even turned out the light.

_____

 

_July. 1994._

Castiel inhaled a shaky breath when he pulled away. The skin of his mouth was tingling with cold, and the sweet whisper of breath that moved across it. The man was still so close. Castiel watched in silence while he touched long fingers to his lips and caressed the surface like he could somehow hold Castiel’s kiss in his hand. His eyes were wide and impossibly green, reflecting the deep hue of the sea. Castiel stilled when he thought about all the wonders those eyes must have seen. The man stared back for the briefest of moments. Suddenly pushing himself up the sand on his tail, his mouth searching for more.

An unexpected surge of desire caught Castiel unprepared. He made a soft noise when he reached out to wrap his fingers in the long damp strands of hair falling around the side of the man's face. His desperate touches were returned without hesitation and he felt the sensation of a smooth, wet palm snake around the side of his neck. Castiel could feel the ends of searching fingers slip under the edge of the material and down the line of sensitive skin that covered the dip of his shoulder. Their mouths met again. Castiel could feel the heat start to rise up deep inside his body. He wanted to lay the other boy down flat on the sand and cover that wet body with his own. Castiel could have lost himself forever in those eyes. He stopped, and just for a second he wasn't sure why he kissed him at all. He didn’t even know his name.

_____

 

_August. 1985._

Castiel waited a few minutes until he was sure the boy had taken all the pieces of bread he threw into the sea. He could feel a tingle of excitement rise up through his small body while he waited in the shallows to see if his new friend would reappear. Castiel saw him swimming a few metres off shore, so he waved a hand and smiled. The boy didn’t wave back. He was just watching Castiel carefully from the safe distance of the sand bar. Castiel wondered what it must be like to live in the water. He always found it far too cold at the start of every summer when he first dipped his toes into the breaking waves. The boy didn’t seem to mind.

Castiel had never seen anything quite like him before. He saw pictures of something called _mermaids_ in the book his father gave him for his eighth birthday last September. He was sort of like that, but there was something so different about him. Castiel was fascinated by the boy. The way his sleek body cut through the waves, how his skin glistened in the sun as the light caught the droplets of seawater resting on his shoulders when he rose and fell with the movement of the tide. He seemed to be just as interested in Castiel in return. When he was close, he would tilt his head inquisitively and seem to study the movement of Castiel’s mouth while he formed shapes around the few words he used to try and communicate with him. Castiel had abandoned that idea when it was clear he didn't understand much of anything he said. He was much more receptive to the gentle tone of his voice. Castiel noticed the boy would sometimes send out short clicks and low vibrations into the water. Sometimes he dipped his face under the surface. Castiel could see the rise of his tail when he lifted it up. He seemed to be looking for something, or someone maybe. Castiel dismissed the thought quickly, when he was distracted by a swift movement that signalled the boy's return to shore.

He resurfaced only metres away, carrying something in his hands. Castiel waited for him while he rode one of the waves in. When he was almost at the edge, the lower section of his body was more clearly visible and Castiel could see the small smooth rise at the top of his tail. He was surprised to see he had an expanse of soft skin, covered by a smattering of shiny scales. The boy pushed his hair back from his face when he slid up the sand in front of Castiel, depositing a few pebbles and some pink shells on the soft ground. Castiel instinctively lined them up in a neat row, but the boy just frowned and rearranged them so they were laid out in front of the space where Castiel was sitting in order of size. The boy picked up the largest shell. His fingers were very long and seemed to taper off slightly at the ends. Castiel could see the outline of pointed knuckles just under his skin and the nails on both hands were long and sharp. He made a low sound into the curve of the shell, holding it close to his mouth. He suddenly thrust the shell towards Castiel and gestured for him to put it to his ear. Castiel slowly lifted it up to the side of his face, his eyes searching the other boy’s expression for silent confirmation. He smiled a little when he shook the shell in his hand and held it closer to his cheek. His smile grew wide when he heard the faint whisperings of the ocean.

“Hey! Hey, I can hear the sea.” Castiel cried excitedly. The other boy was still studying him. He almost mirrored Castiel’s smile perfectly when he reached forward and wrapped his hand around the shell where it was pressed against the side of Castiel's face. He warmed at the contact and stroked his thumb over the boy’s fingers while they sat together at the edge of the water until the sun started to dip close to the horizon, casting a pattern of swirling orange shadows behind them.

_____

Shaw was hurrying down the harbour behind Smith, when he started to get ahead of him.

“You can’t do that.” Shaw repeated again, but Smith just marched down the jetty with his metal case in hand. Marshall pretended not to have heard him, picking up his pace to head off down towards the boat where it was still tied to the platform. “Smith?” Shaw tried again. His voice was more insistent this time. Marshall was almost at the water. He turned around with a sigh and looked straight into those deep brown eyes. He waited for Achak to just get it over with already so he could move on. “That’s not what this project is about.” Shaw spared a quick glance across the ocean. “Castiel won’t like it.” He warned. Smith looked him up and down with narrowed eyes. He seemed to be studying him intently, like Achak was one of the specimens under his microscope.

“Castiel Milton doesn’t really have a lot to say about anything at the moment.” Smith replied coldly. “This is my investigation now. When he comes back, I may review it. You’re the photographer so - _photograph_.”

Shaw frowned hard while he processed the implications of that. He felt a twisted warning pull in his stomach when his gaze moved to the shiny rectangular box being carried onto the boat. Smith might have claimed there was probably nothing conclusive on that tape, but he still packed enough sodium thiopental to take down almost anything.

_____


	7. Affinity

**Summary for the Chapter:**

> Castiel makes a desperate attempt to get back to the institute before the investigation changes direction. He fears someone may attempt to pursue and capture whatever is swimming off the coast. Castiel remembers happier times when he formed a special bond with the boy from the water that will never be broken.

**Affinity**

Castiel blinked when the dawn light filtered in through the window, faint glow of early morning helping him to make out the contours of the room. Castiel was very thirsty. He reached out a weak hand to feel for the cup of water by his bedside, pushing himself up on his elbows to lift the container to dry lips. He gulped down a mouthful and swallowed loudly. His whole body ached.

Castiel flinched when he tried to sit up properly. There was a pain in his chest that soon faded to a dull ache behind his ribs when he moved. Weariness fell from him when he realized where he was. Castiel groaned and rubbed the back of one hand across his eyes. He felt a sudden consuming need to get back to the institute, but he couldn’t really explain why. There was just a strange feeling of unease playing with his thoughts. Castiel couldn’t really remember how he got there. There were flashes of disjointed and inconsistent images. He pulled his last clear memory to the front of his mind. He was jumping into the water and struggling to stay above the surface. Castiel could vaguely recall something push him up from beneath the waves when his vision started to dim. Castiel remembered breaking through the waves and trying to catch a deep breath before everything went dark.

Castiel quickly shed the hospital gown and searched frantically for his own clothes. Someone must have dried them, and folded them in a neat pile inside the cupboard. He still felt dizzy and swayed slightly when he bent down to pull on his pants. He rested one hand against the side of the bed while he struggled to get dressed. All he could think about was getting back. Castiel tried to calm his stilted breaths when he opened the door and crept down the corridor. He wasn’t sure they would let him go, so the only option was to sneak out. He clung to the wall while he made for the stairs, checking up and down the narrow hall in both directions before sliding his hand around the edge of the door and easing it open. Castiel slipped through the gap and raced down the steps, pulling off the plastic bracelet with his teeth while he ran. It snapped free, and he spat it on the floor. When Castiel reached the main doors, he pushed them open with trembling hands and didn’t look back.

_____

 

_July. 1994._

Castiel leaned back on the sand and studied the face of the young man who was now watching him with a confused and almost hurt expression. Castiel had pulled away so suddenly, it might have looked like he didn't want it. He was still taking in heavy breaths of air and trying to process exactly what he felt when he stole that kiss. Castiel was shaking. He couldn’t be sure if it was from the cold, or from the sensation that flowed through his body when he pushed his mouth against those slick, moist lips. It only made Castiel want more, but there was caution spiralling through his thoughts while he looked at him. No, Castiel _did_ want more.

The desperate look in those green eyes that stared back at him made him shift slightly, leaning his body closer to the edge of the water where the man was waiting for him. He looked totally lost. He seemed to be expecting Castiel to do something. Kiss him again. Leave. He wasn’t sure which. Castiel just wanted to hold him, wanted to try and explain, but he knew whatever he said would mean little. The man couldn't understand him, and Castiel had no idea how to interpret the strange sounds that poured effortlessly from the other man’s mouth. He thought maybe he should try and communicate with him some other way instead. Castiel got his attention with a gentle press of one palm against his cheek. He lowered his hand slowly, making sure those beautiful eyes followed the line of his fingers when he dropped them down to the other man's chest and tried again.

“Castiel, remember?” He said clearly, carefully pronouncing every syllable. The man seemed to understand, but he didn't have the capacity to form words in the same way. He had evolved to live in the deep ocean where he needed the sounds to carry through the water. He used them to create echoes from every surface to help him navigate the dark places under the waves where the sunlight could never reach. Castiel felt his heart flutter at the thought of how graceful he would look diving through the pretty coral arches that lined the bottom of the sea. He tried to free himself from so many distracting thoughts when the man wound his fingers into the front of Castiel's shirt. He was finding it increasingly difficult to focus on what he was trying to accomplish when that gaze was pinning him tight and demanding his attention. Castiel placed one finger against the pale chest. He could feel the muscles twitch underneath the skin at the contact. The man didn’t move away. His features softened, and the confused frown faded when his mouth broke into a gentle smile. He looked like he was starting to form a word. His mouth moved open and closed around a sound he seemed to be struggling to get out. Castiel realized he was attempting to emulate the intonation in his voice. The man was trying so hard to tell him something, and Castiel felt a surge of pity. He was watching Castiel’s mouth. He lifted his fingers and rested the ends against his bottom lip. He caressed it, and Castiel wasn’t sure if he wanted him to help, or kiss him again.

Castiel nodded in a gesture of understanding, willing him to try and say whatever was trapped behind those perfect lips. He could see the small ripples moving in his neck when the man emitted a low note that resonated in his throat. He trapped his tongue behind his sharp teeth and clicked it forward. Castiel could see the frustration building on his features. Eventually he managed to form something more recognizable. Castiel caught the first extended click, which was followed be a long drawn out call.

Castiel tried to make sense of it. The man was trying to tell him his name. The first tap against his teeth sounded like a letter. Castiel listened intently while he repeated it.

“D… D…e a n.”

Castiel couldn’t resist a pleased smile while the word developed on his lips. They were just clicks and sounds, and Castiel knew he didn’t really understand, but he had to call him something and that seemed as good a name as any.

“Dean?” Castiel smiled. “I like it. I will call you Dean.” The man’s frown returned, but Castiel soothed him and caressed the skin of his arm with calming strokes. He started to wonder if there were more like him, and why they never came up as close to the shore as Dean had.

_Dean._

The very sound of it made Castiel's heart patter. He felt like he could stay there forever just gazing at him. He looked human, but for the soft hint of blue-grey tones to his skin. Camouflage. Castiel presumed, while he studied him. He inspected the spread of small sandy patches that covered his shoulders and part of his face. They looked like freckles in the sunlight, even though they were probably just markings to help him conceal his body against the sand of the sea bed. He must have to protect himself from predators, Castiel thought. He liked them anyway. He liked everything about him. He was the poster boy for masters of evolution, and Castiel even adored the cute little points of his ears that helped him triangulate signals in the dark ocean. He was beautiful, and Castiel was completely lost.

_____

Smith left his precious aluminium case inside the cabin and locked it shut. He was staring hard at Shaw while the boat started to pull away. His eyes looked dark and cold. Marshall had no intention of letting Castiel Milton ruin his chances of being the first man to capture a live specimen of an undiscovered species like that. He had tried to push down the constant doubt they probably didn’t even exist at all. There was something on that tape for sure, but it could have been anything. Even if they were real, they were just animals. Castiel would just have to deal with it. If Smith could catch one before he got back, it would be too late for Castiel to do anything about it. The whole world would know of his discovery. Smith would be famous, rich.

All these thoughts were circling in his mind when he pushed down the handle, and the boat lurched forward, spraying up lines of white foam in its wake. Smith had already secretly contemplated some of the experiments he could do to help him understand such a species. He might have to tell a few lies to get round some of the human and animal rights bullshit, but that was okay. It wasn’t like he hadn’t done it before. A cruel smile started to spread across his face. Milton was out of action for now, and the sooner Smith managed to net something and take it back to the institute, the better. He may not have a lot of time and Castiel would be pissed when he found out what his true intentions were. Marshall may be a brilliant animal behaviour expert to all those around him, but deep inside his dark mind he was a heartless, sadistic bastard.

_____

 

_August. 1985._

Castiel was still wiggling the pink shell next to his ear when the daylight started to fade. He knew he would have to go back to the house soon, and he really didn’t want to. He didn’t want to leave the boy alone on the cold sand. Castiel needed him to know he would come back to him, that he wanted to see him again. He lifted up his hand and spread his fingers across his chest.

“My name is Castiel.” He tried slowly. “C a s t i e l. Do you understand?” He asked, but the boy didn’t even make a sound in response. He was just staring, as usual. His eyes were fixed on Castiel’s mouth while it moved around the words. “Never mind.” Castiel added with a sigh, looking out across the rolling sea. He felt a sting of disappointment, but he tried not to let it show on his face. He only had three weeks left. He would be able to try again tomorrow, and the next day. There were things Castiel wanted to know about the boy too.

Where did he live? What was his name?

_Would he miss him when he was gone?_

All these questions he wanted to ask would have to wait. He didn’t even want to think about leaving. Castiel knew the strange boy couldn’t understand him very well yet. Since they met, they communicated in gestures and expressions, and the soft tone of his voice. All his efforts to talk to the boy had been met with clicks and whistles in return. In some strange way, Castiel thought maybe he understood. Castiel could tell a lot about that boy just from looking into his eyes. Maybe he was lonely too.

Castiel crossed his legs and rested the shell on his lap. He smiled and reached out one hand. The boy wrapped his fingers around Castiel’s and pulled himself up the sand. Castiel hadn't really looked closely at his tail before. He suddenly wanted to touch it. It was thicker than he imagined, and the place where it joined the rest of his body was almost indistinguishable. The scales seemed to blend perfectly into the skin of his back. They shimmered when he moved and reminded Castiel of the little fish he chased in the streams back home, when they blinked and glistened as the sunlight filtered through the water and made them sparkle.

The thought was pushed to the back of his mind when he reluctantly stood up and brushed the sand from his clothes. The boy leaned forward on his tail and slid himself a little further up the beach like he wanted to follow Castiel home. Castiel felt a horrible sick feeling twist in his stomach when he realized he would have to leave him. Castiel could hear his mother calling him from the balcony. He was terrified she might see the other boy in the half-light of the early evening. Castiel hurriedly tried to push the other boy back into the water and encourage him to swim out to sea. The wide green eyes just gazed back up at him, and he didn’t move. Castiel tried hard to ignore the desperate pleading he saw reflected there.

“You have to stay here.” Castiel said sadly, placing his palms gently against the boy's chest and trying to guide him back to the shallows. Castiel felt his eyes start to fill with frustrated tears. “I’m sorry, I have to go.” Castiel continued, as calmly as he could manage between the breaths that were caught in his throat. Castiel backed away from the edge of the water and clutched the shell the boy had given him. Its sharp points were digging into his fingers as he gripped it tight. “I promise I'll come back tomorrow!” Castiel shouted. He turned and ran all the way back up to the house before they sent out a search party for him. Castiel didn’t look back. He knew even then if he looked into those eyes for too long, he would never be able to refuse that boy anything.

_____


	8. Validation

**Summary for the Chapter:**

> Castiel is stunned by a revelation from Shaw and they both head upstate to learn more about the water spirits. Meanwhile, Smith is determined to capture a specimen to study at his leisure. Castiel realizes too late, the damage spawned by his desire and obsession has already been done.

**Validation**

Castiel reached the institute in less than an hour and rushed straight to his office. He was out of breath, face flushed and damp from exertion. He still felt light-headed, finding it increasingly difficult to focus when he reached for the stack of papers on his desk. Castiel started sifting through them in search of something - anything that would help him find out what Marshall had been up to in his absence. Castiel was determined to set his partner straight on the focus of the investigation, still busy looking at the case file when he heard footsteps behind him. Castiel turned to see Shaw approaching. He looked relieved to see him.

“Milton, thank God.” Shaw breathed. He came closer and started tugging at Castiel’s sleeve.

“What’s the matter?” Castiel asked quickly, a sense of dread washing over him. He let Shaw pull him out into the corridor.

“Smith took the boat out. I don’t know what he was thinking. He seemed pretty determined.”

“On what?” Castiel asked in alarm. They hurried down the stairs.

“He wants a live one.” Shaw answered, pushing the main doors open so Castiel could take a deep gasp of fresh air. He was shaking his head, scanning the bay with narrowed eyes.

“But he doesn’t even believe, not really.” Castiel sighed. Shaw gave him a knowing glance, gently resting one hand on Castiel’s shoulder.

“But you do?” Achak asked quietly. Castiel met his gaze. There was something behind his chocolate eyes that was honest and open. Castiel nodded.

“I do. I really do.” He replied. Castiel couldn’t tell Shaw why, of course. Not yet. He couldn’t risk telling anyone the truth. The reason he was here. His reason for everything. How he missed him. There was nothing Castiel wouldn’t give to see those green eyes again, but he couldn't take his freedom. Castiel could imagine all the terrible things Smith and others like him would do to Dean if they got the chance. He felt horribly sick.

“Castiel?” Shaw prompted suddenly. “Can I ask you something?” Castiel swallowed hard, his heart beating fast in his chest. “Do you believe, or do you _know_?” There was a tense silence while Castiel made sure he understood what Shaw was asking. He didn’t answer straight away. He was still looking out across the waves. “Why do you think I took this job?” Shaw asked, after a brief pause. Castiel shrugged. He didn’t want to answer in case he said something he might regret. “I have seen them too.” Shaw added. Castiel stared at him in stunned surprise. He tried to stammer a response, but he couldn’t get the words out without them catching in his throat.

“I’m sorry?” Castiel faltered. Shaw smiled.

“It’s okay, you don’t need to worry. I want to protect them, too. The only reason I wanted to work here in the first place was so I could sabotage your operation.” Achak laughed. Castiel was gaping at him in shock, blue eyes wide and unblinking.

“What?”

“I've seen them upstate sometimes. They're beautiful creatures. All they want is to be left alone. Not hunted, _studied. _” Shaw continued in a whisper. Castiel could see the look of disgust in his eyes when he glanced out to sea. “I saw them first when I was a boy. They seem to come up to the bay once every ten years or so, I don’t know why. They stay for a few weeks, and then disappear again. I always thought it must be something to do with their mating cycle.” Castiel was staring at Shaw in amazement. A thought suddenly struck him. Dean hadn’t left him alone all those summers by choice - he was with his pod. Every time Dean returned to the bay he came to find Castiel. He felt even more sick when he realized the last time Dean would have come back, Castiel hadn't been there to meet him. He wondered if Dean waited at the beach for him. A wave of nausea washed over him again. His eyes started to sting. He was the one who never returned. Castiel thought Dean had left him, and he couldn't go back. It was all too painful. Castiel swore to himself if he ever found him again, he would tell Dean how sorry he was and never let him go.__

“Oh, God.” Castiel muttered. Shaw held out one hand to steady him.

“You okay? You look a little pale.”

“God, what have I done?” Castiel whimpered, imagining his beloved merman lying on a cold steel table with needles sticking out of his beautiful soft skin, and people leering over him waiting to take tissue samples. “I need to go there, Shaw.” Castiel said at last. “I need you to take me to them.”

_____

Smith already anchored the boat and was sitting one side of the deck seat with the aluminium case open and wedged between his knees. He was putting together separate sections of the dart gun while he searched the surface of the ocean with sharp eyes.

 _Fuck Castiel._  Smith thought, loading the cartridge of tranquilizer into the barrel. He was going to do this his way now. Milton had always been too obsessed with doing things properly, protecting endangered species, conducting his investigations with sickening professionalism and never taking all the credit for new discoveries. Smith had never really believed in the aquatic ape theory, but if they _were_ real, he wanted one. Smith waited an hour at least, before he noticed even the slightest hint of movement beneath the waves. He was cold and frustrated, and thoroughly pissed. He had absolutely no patience at the best of times and was growing increasingly irritable as he tapped the gun on his knee, waiting for something to come close enough to be an easy target.

Maybe Castiel _had_ imagined it. The evidence was far from conclusive, and the video and stills were dim and out of focus. Smith cursed, before wandering over to the side to spit into the water. He stopped. Something dived underneath the boat. It was blue-grey and sleek, and it changed direction quickly. Marshall fumbled with the gun and aimed it blindly into the waves. He stared down the sights and waited until he had a clear shot. He couldn’t miss. He couldn’t scare it away. He could see the swift and purposeful movements like it seemed to be looking for something. Marshall gasped when he saw the flick of a thick tail break the surface with a spray of foam. He smiled as he raised the gun and fired.

_____

“How far is it?” Castiel asked again. He was sitting in the passenger seat of Shaw’s truck while they bumped and swerved down the dusty back roads that wound up the coast towards Peter Dana Point. He was clearly agitated, and kept rubbing his palms down the front of his jeans.

“Relax.” Shaw replied, without answering the question.

“I can’t. You have no idea how long I've waited to see him again.”

“Him?”

Castiel hesitated. He forgot himself for a moment, but recovered quickly.

“I meant, I would really like to see if it's the same one I met as a boy.”

“You saw one too, huh? I thought you must have.” Shaw nodded thoughtfully. “I know you think they're some sort of new species of human or whatever, but that's not what we think. There is spirit in everything, Castiel. The water is just another part of the same world.” Castiel was watching Achak intently. He imagined there was a lot more to the man sitting next to him than the ability to take a good camera shot.

“Actually, I think as a species they’re probably a lot older than us. I’m a scientist. I can’t help but think like that.” Castiel smiled.

It took them about two hours to travel up the coastline. Castiel was anxiously scanning the horizon the whole time. Shaw already told him the reservation was further inland, and they might head up there later if they had time. Honestly, Castiel was too excited to care. As they pulled up, Castiel could see the sea was hidden behind the rise of the cliffs. He was desperate to get down to the water.

Castiel didn’t dare to hope he would see Dean here. He was usually swimming further south and even with his amazing skill in the water, it would take him a few hours to move between the two bays. Castiel tried to swallow down a feeling he couldn’t quite define, while he stumbled down the rocky slope that reached down to the sand. Shaw was close behind him. About half-way down, Achak shouted Castiel’s name. He turned and shielded his eyes from the bright glare of the sunlight. Castiel could see Shaw was pointing down the beach to a small inlet that was mostly hidden from view.

“Down there, behind the rocks.” Shaw called, against the noise of the crashing waves. “There’s a cave set back from the beach.”

Castiel nodded silently, still making his way down the bank. His feet were slipping on the sharp stones and causing a few of them to tumble down the hillside. Castiel didn’t even wait for the other man to catch up, and his feet soon touched the wet sand. The tide had only just started to recede, and there were still little hollows filled with fresh seawater dotted about the shoreline. Castiel saw a small shallow stream leading from a gap in the rocks, and down to the edge of the water. Cautiously, he followed its path up the beach and spotted a dark hole in the side of the cliffs. Castiel ran towards it without thinking, his heart pounding so fast he could hear it. Castiel could feel a rapid pulse throbbing in his neck by the time he reached the cave entrance.

Castiel hesitated, trying to remain calm and approach carefully. Castiel was terrified of scaring anything that may have been hiding inside. He silently prayed there was at least one of them there. _Dean._ Shaw reached him while Castiel was waiting outside the cave, attempting to still his heavy breaths of fear and excitement. Shaw nudged Castiel forward with a gentle push of one palm against the middle of his back.

“No guarantees, Castiel. It’s usual for at least two or three to be here this time of year, but they might be out hunting, or they may have left already. Most of their time is spent in the water.” Shaw added.

“Two or three?” Castiel echoed in amazement. “I didn’t realize - ” His voice trailed off, soon lost to the breeze. There was only one he wanted to see. One that haunted his dreams and pulled at his heart whenever he thought about those perfect eyes staring at him in wonder.

Castiel inhaled a deep breath, slowly creeping forward. He hardly blinked at all when he got near the entrance. He could hear faint splashes coming from inside and was muttering encouragements to himself in between offering up whispered supplications to the heavens. Castiel climbed over the irregular rocks that lined the mouth of the cavern and peered into the darkness. He gasped when he looked into the shallow pool that was hidden in the shadows. He could see the silhouetted forms of something in the water. The reflection of the shiny surface lit up their smooth bodies, and cast growing shadows onto the rough grey walls of rock enclosing them. Castiel could just make out two distinct forms against the wall. One was much larger and lighter in colour. Castiel thought the other one could have been a female. It was smaller, and more delicately formed, but most of the lower part of the body was obscured from view where it rested under the surface of the water. His heart sank. Dean wasn’t there.

Swallowing down his disappointment, Castiel turned his attention back to the creatures in the water. They seemed to be cleaning off the sand in deliberate strokes, and Castiel could hear the low sound of occasional clicks and drawn out notes that suggested they were communicating with each other. It reminded him of the days spent during the last summer he had with Dean. Castiel managed to teach Dean a few words, but his mouth had always found it difficult to form the right shapes. _His mouth_. Castiel was lost again. He smiled at the memory. It was bittersweet. While he watched the scene in front of him, his amazement suddenly turned to panic. It rose up and spiralled through his chest. He caught his breath. Dean wasn’t here, and Smith had set out hours ago. He knew Castiel had seen something that made him jump into the water. Shit. He had to get back. He had to get back _now_.

_____

The return journey seemed to take even longer. Shaw wanted to wait, but Castiel was so insistent, Achak had only been able to appease him at all when he agreed to take him back to the institute. Castiel was restless the entire journey, and kept mumbling and cursing to himself all the way back. Shaw only caught odd snatches of what he was saying, but he could tell Castiel blamed himself for everything. He looked tired and pale, a deep sadness behind his eyes.

Shaw hadn't even turned off the engine before Castiel flung open his door, and was leaping out the vehicle. He sprinted up the steps two at a time, not even slowing down when he reached the top. Castiel thrust the main entrance open and ran through the hallway and up the first flight of stairs until he reached the main office. Castiel felt everything stop when he swung open the door. There were people. So many people. There was a wash of noise, but his base senses had almost shut down completely when he started to move through the crowd. Someone spotted Castiel and grabbed him by the shoulder.

“Milton, you’re here at last.”

Castiel felt a hundred emotions drench him, stumbling forward and trying to pull himself free. He looked at the man with confusion in his eyes.

“I don’t understand.” Castiel murmured, a sense of dread coming over him.

“Smith did it. He got one.” The man smiled at him with delight, and it was all Castiel could do to prevent himself from falling. He reached the front of the group and stopped dead, frozen to the spot in horror. In a large rectangular tank that took up most of the room, he could see the curved form of one of the creatures curled in on itself in one corner. The tail was moving wildly in small circles of distress and trembling arms were wrapped tightly around a smooth body. Castiel stopped breathing when he saw the head turn slowly at the sound of his voice. He stared into those green eyes his heart had longed to see just one more time.

“Oh, God... no.” Castiel whispered in despair.

_Dean._

_____


	9. Misery

**Summary for the Chapter:**

> Castiel is tormented by the guilt that consumes him. Dean is now captive and alone in the heart of the institute. Castiel fears he might have to continue the investigation so he can remain close to Dean, but it soon becomes clear people there are prepared to do anything to find out all they can about this mysterious creature.

**Misery**

Castiel and Dean stared at each other for a moment like neither of them could quite believe what they were seeing. Dean seemed to lift himself up on his tail the second he saw Castiel. He recognized the sound of his voice. Dean turned his body in a graceful arc, pushing his face towards the side of the tank. Castiel knew at once he remembered him and ran forward without thinking. His heart was beating wildly when Castiel quickly pressed his body up against the glass, hands smoothing over the sides. He could feel his fingertips dampen from the contact. Dean was looking at him helplessly through the side of the tank. His eyes were wide while he stared at Castiel with that unblinking green gaze he had missed so much. Castiel could see the futile hope there while Dean watched him. He never felt so sick in his entire life. Castiel knew he couldn’t help him, not yet.

Dean’s mouth curved up slightly at one side, a gesture Castiel had seen him try to mirror before. Castiel made a sorry attempt to return the smile, but his heart was so heavy he found it difficult to even pretend he was happy to see Dean there. Castiel had spent years hoping to find him, longing to see him again, but not like this. This was cruel and unforgivable, and he felt his own guilt twist in his stomach like a knife.

_Why did it have to be him?_

Smith walked over to Castiel, greeting him warmly when he patted him on the back. Castiel felt himself cringe under the touch.

“I think it likes you.” Smith laughed, prodding a finger towards the glass. Dean recoiled, watching Castiel even more closely through sad eyes.

“Why?” Castiel breathed. “Why did you take him?” He asked again, deliberately stressing the fact he resented Smith referring to Dean as an _it._ Smith looked at him with a frown deepening on his brow.

“Well to study it, of course. What the hell's the matter with you?” Smith asked harshly. ”Milton, all these years you’ve been chasing for evidence they exist, and now you’re asking _me_ why?”

Castiel dropped his gaze. Those words cut deep. Smith was right. Castiel didn’t dare say anything right then. If he protested too much, they would just get rid of him and then he would never be able to help Dean. He _needed_ to be there. Castiel swallowed down the bile rising in his throat and forced a smile.

“Yes. Yes, of course.” Castiel muttered, turning his face away. He couldn’t even bear to look at his friend. His eyes were soon drawn back to the water. Dean lifted up one hand to the glass and pressed it against the side so hard Castiel could see the labyrinth of lines underneath, and the soft blue webbing between his fingers where they touched the barrier between them. Castiel stifled a sigh of regret, placing one hand up to cover Dean’s. They stayed there for a moment with their palms pressed together, not touching. It was all Castiel could do not to climb into the water and hold Dean close.

Castiel had failed him when they were eight years old and he couldn’t keep him. He had failed him when they were seventeen and all he wanted was to love and possess him, but he let Dean swim away. Castiel had failed him ten years ago when he never returned to Winter Harbour for fear he couldn’t take the disappointment of Dean not being there again. Castiel wouldn't fail him again. He would have to make Dean understand something he had always wanted to tell him. He had been a part of his life for as long as he could remember. Castiel glanced over at some of the others gathering around Smith while he told them, yet again, how he'd discovered the only specimen of this new species. Castiel wasn’t really listening. His focus was on Dean, and how he could possibly make him believe he had nothing to do with his capture, how much he wanted to free him. That was all Castiel had ever wanted, for Dean to be free.

The last time they were together, Castiel tried to make Dean understand why he couldn’t keep him. That day had weighed heavily on him for almost twenty years. His mind drifted back to the misery of that memory, while Castiel stared though the glass at the man he had given up so he could be free. Yet here he was, caged and alone.

_____

 

_July. 1994._

Castiel already packed one case and left it outside the bedroom door for his father to load into the car. He made time for one last walk on the beach. Castiel knew he would be gone by morning, and he wanted to tell Dean he would come back for him. Castiel finally managed to help him form a few words over the summer and Dean was getting much better at reading emotions and expressions. Castiel had even tried to get Dean to help him interpret some of the sounds he used in the sea to communicate, but it hadn’t been very successful. Dean seemed much better at picking up fragments of human language, so they focused on that.

Castiel spent most of his days with Dean in the week after they pressed their mouths together for the first time. Dean seemed to expect it, and Castiel was always happy to indulge him. They never got much further than exploratory open-mouthed kisses and Dean had been fascinated by Castiel’s legs. Castiel loved the way Dean would run his long fingers down the skin of them and dip them in between his toes. It tickled, and always made Castiel laugh but he never pulled away. He could never refuse Dean anything.

Castiel put off hinting he would be leaving soon for most of the afternoon. Dean hadn’t seemed to notice how distracted his friend was. They watched the sunset together and Dean returned to the water to find Castiel an especially beautiful shell to remember him by. Castiel smiled wide when he examined it, and Dean leaned into his side and wrapped his arm across Castiel's thighs. Castiel warmed at the memory of Dean’s slick body pushed against his skin. It was then when he felt the hard press of a firm swelling at the front of his tail when they had lain together on the sand, with Dean's soft lips smoothing kisses down his neck. Castiel had pulled away then. He was scared. He wanted Dean, but he knew it would be another year before his family came back to the beach house and Dean wasn’t there every summer, anyway. Castiel had never made the same connection Shaw had. Dean tried to follow him up the beach again that night. Castiel felt so sad for him when he attempted to shimmy up the sand, his little scales catching on the pebbles as he moved. Castiel had run back to him again, just like he had when he was eight years old, desperate to explain not everyone was like him. Some people wouldn't care about Dean the same way Castiel did. The world could be a dangerous place for someone who was different. Dean waited for him in the shallows and Castiel had drawn pictures in the sand with his finger to try and show Dean he had to stay there and wait for him. Castiel made an image of the sun and the earth, and the movement of the tides. He was pretty sure Dean understood when he finally dragged himself back to the sea and smiled. Dean raised one hand in farewell before he flicked his tail on the surface of the water and disappeared from view for the last time.

_____

Castiel's mind was suddenly pulled back to the present by a swift movement at his side. Someone in a white lab coat he'd never seen before pushed past him and moved round to the far side of the tank. Castiel could see a covered syringe in one hand. Some of his feelings must have shown on his face because when he looked back at Dean, he had one hand spread over his heart and one on the glass. Dean pulled it away and pointed upwards with a long finger. His eyes moved up to the rim of the tank. Dean wanted Castiel to get him out.

“I can’t.” Castiel mouthed, as quietly as he could in case one of the others heard him. Dean was frowning, his mouth set in a tight line. He pointed up again and pressed his hand once more to his chest. Dean was watching the movement of people outside the glass. His eyes started to dart between the moving shapes, soon growing wide with fear. Castiel could see Dean making small circles on the floor of his tank with the end of his tail. He was scared. Castiel tried to calm him with his voice when someone came in carrying a long pole with a cold metal hook at one end. “Hey!” Castiel shouted in panic. “Who are you? What are you going to do with that?” Marshall strolled over to Castiel and rested one arm around his shoulders.

“One of my new recruits.” Smith said calmly. “Well quite frankly, your team was a little green, Castiel.” He continued. “I'm going to let the photographer go too.” Castiel stared at Marshall with rising alarm.

“What? _Why?_ ”

“Well, I think collecting photographic evidence to support your theory is now a little redundant.” Smith nodded over to the tank before Castiel started to back away. He was desperate for air. “Wait, I want you to stay for this.” Smith said suddenly, dismissing all but two of the others with a wave of one hand. Castiel could see Dean was still pleading to him with his eyes. All Castiel could do right now was to try and stay close. If that meant sucking up to Smith and pretending he intended to carry on with the investigation, then so be it.

“Marshall.” Castiel tried, as calmly as he could manage. “We don’t need to use that. Why don’t you let me see if I can get him to come to me?” Smith was watching Castiel intently. For a moment he held his breath, his heart beating too fast. Castiel had to be careful. He had seen the marks on Dean’s back when he turned. Four deep puncture marks where he was shot by the darts. Small bruises had formed in little circles around each hole and they looked red and sore. Castiel wanted to try and prevent anyone from causing any more damage to that beautiful body.

“Why?” Marshall asked suspiciously. He put one hand up to stop the man from dipping the pole into the water and moved closer to Castiel.

“No reason.” Castiel replied. “Maybe he would just be more cooperative if we didn’t hurt him.”

Marshall looked at his friend through narrowed eyes. He seemed to be reasonably satisfied with the explanation, but his gaze was fixed on Castiel when he moved back towards the tank. When Castiel climbed the steps and leaned over the top, Dean swam up to him almost immediately. He wrapped his fingers around the edge of the glass and made soft keening sounds in the back of his throat when Castiel touched the skin of his arm. Dean was trying to say his name, but it was rushed and desperate. All that came out was an unsteady _'Cas'_.

“That sounds like it's trying to get your attention, Milton.” Marshall glared at Castiel. He set his lips in a tight line and tried hard not to say anything he might regret.

“He's just hissing. How could he possibly know my name?” Castiel replied cautiously. “I think he's getting really agitated.” Castiel leaned over a little more, and tried to soothe Dean by gently rubbing his palm across the rise of his back, careful not to touch the inflamed areas where the darts had left their brutal signature. He could see Dean was waiting for him to do something more. Castiel panicked when he realized Dean was leaning in for a kiss. Castiel coaxed him forward with the same motion he had used all those years ago when he first saw him as a young boy. Castiel didn't miss the painful irony of that memory. It now felt bitter and tarnished. He knew he had Dean’s trust, and it was dreadful to have to use that to get him to do what Marshall wanted when he should have been thinking about how he could keep Dean safe.

Castiel eventually managed to get Dean to push his body over the top of the glass and helped one of Smith’s assistants to carry him down the stairs and lay him on the steel table already set up for him. It was covered with a thin length of white cotton and Castiel felt his stomach lurch when he saw there were leather restraints attached at both top corners, and a wide one at the bottom designed to wrap over his tail.

“I’m sure that won’t be necessary.” Castiel tried gently, as one of the men moved to hold Dean down while Smith picked up the strap at the end of the table and started to fasten it over his lower body. Marshall ignored him and continued to pull at the strip of leather until it was pinning Dean’s tail to the base. Dean attempted a weak struggle, but Castiel shook his head. He was desperate to let him know it was better not to fight.

“No, it needs to be restrained." Smith replied. "First, I want to see if they're the same as us.”

“What do you mean?” Castiel asked, with growing concern.

“Well, anatomically, genetically. I need to know how they reproduce.” He gave Castiel a cold smile, and started to explore the line of Dean’s stomach until he reached the ridge of scales that signalled the uppermost seam of his tail. Marshall smoothed his fingers down, and dipped them in between some of the scales that were a slightly different colour. He was feeling for an opening. 

“I think we can be certain this one is male.” Castiel argued pointedly, when he saw Dean flinch at the contact. Smith moved his hand over the distention that was gradually becoming more obvious every time he rubbed his palm across it.

“Yes, I can see that now and he’s a big boy, as well. Look.” Smith said, grabbing Dean around the swollen protrusion on the front of his tail. He shook it a couple of times before letting go and laughed along with the others.

“Please, don’t do that.” Castiel whispered through a tense breath. He was the only one who saw Dean inhale a shaky breath and turn his head to one side. Dean closed his eyes shut when a small tear trickled from the corner of one eye and down the side of his face before soaking into the sheet. Castiel waited until the others were preoccupied before trying to get Dean to respond. He wrapped his hand gently around Dean's fingers under the table and silently vowed to himself he would never rest until he managed to return Dean to the ocean.

_____


	10. Disobedience

**Summary for the Chapter:**

> Castiel is desperate for Dean to forgive him for leaving and help him understand he had nothing to do with his capture. They soon rekindle the passion they once felt for each other, but Castiel knows his affection for Dean must remain a secret. He makes good on a promise he made many years ago to protect Dean from the cruel intentions of others.

**Disobedience**

Castiel could feel how much Dean was shaking while he held his hand, trying to comfort him the only way he could for now. Castiel prayed the others would soon lose interest and leave him alone.

“There, so now you know.” Castiel attempted weakly. Smith hesitated for a moment, studying Castiel’s expression. Marshall forced a laugh while his hand rested over Dean’s growing erection. He tried a couple of experimental taps.

“He’s very responsive, isn’t he?” Smith commented, letting his hand fall away. He wiped his palm down the side of his jacket before nodding to the two men with a gesture of dismissal. Castiel didn’t say anything. He was watching Dean closely. “So now I know.” Smith echoed. Castiel sighed with relief when the other man turned around and walked over to the counter to fetch something. Dean shuffled in the restraints and looked up at Castiel with confused eyes. Castiel attempted another smile, but Dean just turned his face away again. He didn’t seem to understand why Castiel was letting people touch him. “Right.” Smith commanded, slowly wandering back to the table. “Get him up.”

“Sorry?” Castiel faltered.

“Get him up. I want to check his back and see how the wounds are healing. I need skin samples, and some blood.” Castiel gently pushed Marshall's arm away from Dean’s body.

“Couldn't we do that tomorrow?” He tried. “I really think he should rest now, Marshall. Maybe find him something to eat?” Castiel knew he was probably giving away more than intended, but he was desperate to save Dean further indignities for now. Castiel really needed to be alone with him. He couldn’t shake that crushing gaze of betrayal that was reflected in Dean's eyes whenever he looked up at him. He felt wretched.

“Yeah, okay.” Smith agreed. Castiel was genuinely surprised by his readiness to abandon his prize catch. “Besides, I have to go make a statement to the press.” Castiel grasped wildly for the opportunity that just got handed to him.

“I can watch him.” Castiel answered, almost too quickly. He was hoping Marshall couldn’t see him sweating.

“Okay.” Smith said slowly. Castiel reluctantly released Dean’s hand and was now running his fingers nervously through his hair. “If you want. I can send someone to help you get him back in the water.”

“No, that’s okay. I can do it.”

Smith frowned at him, but the doubt faded quickly. He was anxious to give an interview and had no real interest in Dean, other than something he could claim. Smith was rapidly losing patience with Castiel as well, and his agitation was starting to show in the way he tapped his fingers against the edge of the table, right next to Dean’s face.

“Fine. Take a few notes or something. I need to know more about its behaviour for my report.”

Castiel deliberately nodded enthusiastically, despite the revulsion he felt at the way Smith talked about Dean like he wasn’t there. Marshall grabbed his coat and took one last glance at Dean before he left. Castiel could hear him descending the stairs, waiting until the sound faded away completely before quickly locking the door and pocketing the key. He rushed back to Dean's side and pulled forcefully at his shoulders, calling his name repeatedly until Dean finally turned his head and looked Castiel in the eyes. All he could see there was sadness and disappointment. Castiel pulled Dean close and breathed in his scent. He could still make out the faint trace of salt on his skin.

“Dean, I’m so sorry.” Castiel mumbled the words into his shoulder. Dean tensed and tried to lean away from him, so Castiel cupped Dean's face in his hands and ran one thumb in a gentle sweep of affection across his jaw. “I didn’t know. I didn’t know they would take you. Forgive me, _please_.” Castiel was gripping him tightly, but Dean’s hands were still resting limply by his sides. He wouldn’t respond at all so Castiel released him, moving round to unfasten the strap still holding him down. Dean shifted uncomfortably and pulled himself a little bit further up the table, but he was trapped. He couldn’t get down safely without Castiel, and there was no space left for him to crawl into. Once his tail was free, Dean curled in on himself and lifted the end of it up to hide his face. Castiel sighed and tried again. He eased the fin down and away from Dean as carefully as he could, dipping his head so that green gaze was fixed on his face and Dean couldn’t look away. A long time had passed since they were together and Castiel thought Dean had probably forgotten most of the words he taught him when they were young. Castiel tried to make him understand using his hands instead. “Dean.” Castiel begged, tilting his face up with a gentle press under the chin, and Dean was forced to look up at him again. Castiel moved his hand over his heart, and balled it into a fist. He struck himself in the chest a couple of times to illustrate how much Dean’s capture had made his heart ache. Dean inhaled a deep breath and reached his hand round his back to point at the stinging marks that were still so clear on his pale skin. “I know.” Castiel breathed, with regret. “I’m so sorry.” There was nothing else he could say. It would never be enough to justify it. Words were easy. Dean was watching Castiel when his expression changed. He really had missed him, never believing he would ever get to hold Dean again. Castiel moved his hand up from Dean's jaw to his cheek and stroked it gently. Dean was finally starting to respond to his touch, twisting his tail nervously while Castiel caressed his face. Dean blinked at him, wide eyes shining with many emotions.

“S o r r y ?” Dean asked quietly, his pronunciation stilted and broken. He _had_ remembered. Castiel said that to him often when they were boys. It had been so easy to say back then.

_Sorry I have to go back to the house now, Dean._

_Sorry I didn’t bring you anything today, Dean._

_Sorry I have to leave tomorrow, Dean._

_Sorry I never came back for you, Dean._

It never really meant as much as it did now. Castiel nodded, tears creeping into the corners of both eyes. He had so much regret. Castiel never really understood why he left like that. He shivered and pulled Dean close, hugging him to his chest. Castiel could feel Dean make a soft hum of acceptance that vibrated against his body. Castiel held him fast and stroked calming touches through his hair. It was shorter than he remembered and seemed to have darkened with age. It was now almost the same colour as the sandy markings that still swept across his shoulders, and Castiel rubbed his palm reverently over them and down into the dip of Dean's spine. He could feel Dean twitch under his fingers while they explored the expanse of skin covering his back. Castiel accidentally brushed their tips against one of the raw marks left by a dart. Dean tensed in pain, so Castiel hushed him and moved his hands further down to cradle the rise of his tail where it dipped underneath his body. Dean jerked his hips forward at the contact and pulled his head back, eyes searching Castiel’s face for something he thought might have been forgotten.

Dean suddenly pushed himself forward and crushed his mouth against Castiel. He wrapped his arms around Castiel’s back, long grabbing fingers twisting roughly into the material of Castiel’s shirt. Castiel could feel himself quickly becoming aroused by all the tiny gasps and soft breaths of want pouring from Dean’s mouth. Castiel splayed his fingers out across the swelling at the back of Dean’s tail and tried to drag him closer. Dean was licking inside Castiel’s mouth with his tongue, and making small controlled thrusts against his side with excitement. Castiel slowly moved around to slip one arm under the bend of his tail and suddenly lifted him completely free of the table and started to carry him back to the tank. Dean pulled his mouth away in surprise.

Castiel had to get Dean back to the water before he lost control completely. He knew if he stayed there much longer, he would want to take Dean. It wasn’t right. Not here, not like this. Dean was pawing at his chest, not understanding why he wanted to stop what they were doing so quickly. Castiel was careful with him as he maneuvered Dean to the steps. Dean was grabbing for Castiel’s belt and plucking at the loops, deft fingers searching blindly for some purchase. Castiel reluctantly swatted his hand away.

“Don’t, Dean. Stop it.” Castiel said, through a smile. He was already half-hard from the kiss, and trying to focus on getting Dean back to the water before he started to dry out completely. “I don’t want to drop you.” Dean had both arms draped around Castiel’s neck while he managed to get him to the edge of the tank. Castiel flipped him over so he dropped in with a splash. Dean moved his tail gracefully through the water, smiling up at Castiel through seductive eyes. Castiel gently pulled Dean's hands free after a few seconds before he dived down to the bottom of the tank in one swift movement.

Castiel watched him through the glass. He'd never seen Dean actually swimming in water before. He was beautiful. The way he twisted his body in effortless circles and curled his tail slightly to change direction. Dean was deliberately trying to get Castiel’s attention, and it was working. Castiel gazed at him through the side of the tank. He just wanted to touch him again.

_____

Castiel woke to a wash of muffled voices and the indistinct clattering of metal. His face was still pressed up against the cold glass, his neck stiff. He rubbed his palm over it and opened his eyes a little wider, blinking rapidly while his vision started to clear. He must have fallen asleep propped against the tank. Castiel tried to catch another glimpse of Dean swimming so gracefully in the water. His last memory before weariness had finally claimed him. His smile dropped straight off and he sat up with a jerk, palms suddenly pressed flat against the glass. He smoothed away the condensation to get a better look and be sure he hadn’t made a mistake.

Dean wasn’t there.

Castiel jumped up and ran for the door, heart stuttering behind his ribs. He almost called out Dean's name, but then remembered he couldn't give them away. Castiel hurried outside and down the corridor, opening doors and checking empty rooms before moving on to the next one. Castiel soon found himself turning in small futile circles, wondering what to do. He stopped in alarm when he heard someone shouting obscenities from down the hall. Castiel followed the sound and pushed open another door that led to one of the smaller laboratories. When he entered, he could see Marshall holding one hand up to his face. There was a clear trail of bright red blood seeping out through the gap between his fingers. Castiel ran over to him. Dean was cowering in one corner of the room with a metal ring around his neck. It was attached to a long steel pole. Dean was hissing aggressively at anyone who came near him, clawing at the air with one of his hands. The other one was pulling and scratching at the circle of silver round his throat. His tail was beating heavy wet thuds against the floor.

“What happened?” Castiel asked breathlessly. He looked stunned.

“The little fucker got me.” Marshall yelled at him, desperately trying to stem the flow of blood from his wound. “Get him, hold him down!” Smith directed, pulling at the other end of the pole.

“Stop it... you’re scaring him.” Castiel said quietly, holding out both hands in front of him and gesturing to Dean that he meant him no harm. Castiel approached Dean slowly and kneeled down next to him. Marshall circled the pole with both hands and used it to push Dean back against the wall. “Hey!” Castiel shouted, when he watched the force of the movement shift Dean’s body across the tiles. Some of the smaller scales were torn off and Castiel could see them littering the floor where Dean had been sitting. Marshall pushed Castiel aside and grabbed Dean roughly by the wrist. He wouldn't tolerate such disobedience. Smith was going to teach this one a lesson he wouldn't forget.

_____

 

_August. 1985._

Castiel got up early the next morning. The shell Dean gave him was resting on the pillow next to his face where he left it the night before. It was the last thing he remembered before falling asleep. Castiel tiptoed quietly downstairs. The house was dark and still. He found it difficult to get to sleep, and couldn’t help but feel guilty he had kept his new friend a secret. Castiel couldn’t keep him. He tried to tell him, but Dean hadn’t understood. His wide green eyes had been fixed on Castiel’s back all the way up the beach until he disappeared from view behind the fence that enclosed the garden. Castiel had watched him for a little while from the balcony after he got ready for bed. Dean was still lying in the foam at the edge of the water, the moonlight reflecting off his shimmering skin. It made him look magical. He had his head tilted back, letting out a long note that hung in the night air. Castiel thought he might have been calling to someone across the waves. Maybe he was just singing up to the dark sky.

Castiel wanted to take Dean home with him. He wanted to keep Dean safe and hide him away from all those people who would hurt him just for being different. Castiel made a silent promise to the stars that night they would always watch out for each other. Castiel would protect him. Always.

Castiel might not have been able to keep Dean that summer, but maybe one day he would be able to make good on that promise.

_____


	11. Penance

**Summary for the Chapter:**

> Castiel tries to make good on a childhood promise to protect Dean while he still remains captive. He starts to formulate a plan that may help return him to the sea. Castiel realizes he should have told Dean his true feelings a long time ago and hopes it's not too late to put things right. These hopes are soon dashed when Castiel learns of a terrible fate that awaits Dean if he stays there much longer.

**Penance**

Castiel was sliding forward on the wet tiles while he tried to keep his balance, making a grab for the pole still pinning Dean to the wall. Marshall was flushed red with anger and spitting curses through clenched teeth while he struggled to decide who he wanted to punish more. Castiel, or the animal that marked him. The sting was bitter. He could still taste the blood when it ran down his cheek and dripped into one corner of his mouth. Smith wiped the back of his hand across it to purge away the stain, and the memory.

“ _Jesus Christ_.” Castiel gasped breathlessly, stomach lurching at the contemptible sight of a trail of damaged scales violently torn from Dean’s body. “What the hell are you trying to do?”

Smith finally relented, and let the pole drop from his trembling hand. It landed gracelessly on the floor with the haunting resonance of metal against tile. The room fell silent. Castiel and Smith were staring at each other with hostility reflected in their eyes. Castiel finally blinked, gently encouraging the other man to release his biting grip from around Dean’s wrist. There were small patches of discoloured skin where Smith had pressed in his fingertips, and Castiel knew they were the beginnings of tiny bruises that would soon develop. Dean’s skin was soft and delicate. It stretched over him so tightly, every curve and sinew could be seen when he moved. His graceful body wouldn't tolerate being mauled and manhandled in such a way, and Castiel knew it.

“Milton.” Smith faltered at last. He was trying to keep his breath calm and steady, but Castiel could see the deep burning hatred for Dean flickering through his eyes. “I don’t want to fight you on this. I can and _will_ remove you, if you continue to obstruct me from carrying out my research.”

“Research?” Castiel mocked in disbelief, rubbing at his arm where it got stretched awkwardly when he grabbed for the rod. “This isn’t research, this is torture and it isn’t right. You have to treat him better.” Castiel murmured, gaze dropping down discreetly to check Dean was alright. He was sitting curled in on himself, his tail pushed up into gentle waves of rent scales and twisted muscles. He looked thoroughly miserable and confused. Castiel’s heart ached for him. Dean still had the metal band fastened about his neck. “Can I at least take that off, and get him back to the tank?” Castiel asked, measuring his tones evenly so he wouldn't alert the other man to how destroyed he felt inside when he looked at Dean. “ _Please_.” He sighed, his expression now soft. Castiel was prepared to play along with Smith’s stupid mind games if it meant that would keep Dean safe. “He's starting to dry out, and he _will_ get sick if you mistreat him, and then you won’t have him at all.” Castiel continued in a whisper.

He ignored the little voice of _and neither will I_ in his head, and tentatively reached for Dean’s hand to calm him. Marshall huffed, pulling the end of his sleeve down over the fingers of one hand. He bundled it up and pressed it to his wound. The blood now formed a dark brown stain on his cheek where it was starting to clot.

“I suppose so.” Smith sniffed indignantly, sparing Dean a casual look of distaste. “It’s no good to me dead.” Castiel swallowed around a tight knot of sadness in his throat at Smith’s constant and deliberate refusals to acknowledge Dean as a man. Castiel leaned over Dean, reaching forward and wrapping his fingers around the clasp of metal. He unhooked it with a click. Dean shook himself free of it and rubbed his long fingers over the skin of his throat where it marked him. There was an angry red imprint encircling the long arc of his neck. Castiel wanted to cover it with delicate kisses and chase the line away. He was suddenly pulled back from that heady thought by the sound of Marshall opening the door behind him. His eyes flicked briefly over his shoulder while he continued to tend to Dean. “But I need it to be obedient.” Smith informed Castiel, a harsh indifference tainting his words. “If you don't teach it some manners.“ Marshall set his mouth in a tight line, his hand resting on the handle. “I will.”

Castiel watched him go, one hand mindlessly fingering the little key he put in his pocket the night before when he watched Dean swim. Castiel frowned.

 _How the hell did Marshall get back in?_ Castiel wondered to himself. Maybe Smith wasn’t acting alone. That thought became a constant worry at the back of his mind. Castiel made sure he locked the door before Dean kissed him, and the memory of the passion Dean pushed into that kiss sent a sudden and unexpected tingle of want straight to his dick. He chastised himself at the impudence of that stray thought, continuing to shift Dean into a more comfortable position. He hated having to be a constant witness to his helplessness. Life must have been so different for him in the blue depths he called home. Here, he was just another defenseless specimen to be studied and shoved at.

Castiel felt like this torment was _his_ penance, not Dean’s. His punishment for letting him slip through his fingers all those years ago. Castiel knew in his heart why he'd done it, but he wasn’t ready to swallow down the denial just yet. He couldn’t keep him. Dean deserved to be free.

_____

 

_July. 1994._

Castiel had been thinking hard about that moment when he pulled away. He had felt something so warm, so shamefully sordid it made him shudder. He wanted more of it. There was just something so inexplicably tempting about Dean. Castiel wanted to take everything he had to give, and make him his own.

_Why had he pulled away?_

Dean wanted him. God help him, he wanted Dean. A treacherous spiral of doubt crept across his clouded thoughts like a shadow, pushing away all those things that made it so right, and replacing them with hesitation and fear. The way Dean made him feel when he kissed his neck and pushed his erection against his thigh. Castiel had known immediately what it was, and had been afraid. He cursed himself all the way back to the house for being so careless in his rejection.

Dean looked so hurt when he rolled over the sand away from Castiel. His heart had been beating fast. Castiel was certain Dean would have let him touch his body, but he just didn't know how to respond to that first hard press against him. Castiel had no idea what to do. He was young and inexperienced, scared to let them get too close. One day he would have to go away and he didn’t know if he could deal with that. It was going to be hard enough to leave Dean for another year. If they formed a sexual bond as well, Castiel didn’t think he could ever be without it.

It wasn’t logical, practical. Dean was the boy from the water. Castiel could never share that world. He had tried once and almost drowned. _No._ Castiel convinced himself. I can’t take him away from his home. Better to end it now, before either of them got hurt.

It hurt anyway. It had crushed Castiel in ways even he couldn’t explain. He remembered how Dean had tried to follow him that night. He looked so lost, the confusion in his eyes pulling at Castiel’s heart and making him hate himself even more for not telling Dean the truth. Maybe things could have been different if he had just said it, shown Dean how much he meant to him. It was something Castiel continued to deny for a long time afterwards. He curled up in his bed that night under a canopy of cotton sheets. Castiel closed his eyes. He forced a deliberate and deceitful thought into his mind to push away his doubt, and strengthen his resolve to leave.

_You are not in love with him._

_____

This was _his_ punishment for not returning ten years ago. Castiel should have made certain Dean had gone forever. That one regret stung more than anything else. Castiel watched Dean slide his tail unhappily across the floor. He was picking at some of the scales where they were stuck to the tiles. Dean ran one hand pitifully along the thick upper flank at the top and slipped them underneath, stretching his neck at a difficult angle to allow himself to view the damage caused by the force of it. A myriad of fractured thoughts tumbled around in disjointed pieces in Castiel’s head. Having to watch such a beautiful creature become confined to the bleak clinical wasteland of this now hateful building was almost too much for him to bear.

 _His_ penance. _His_ fault. Castiel should have told Dean how he felt a long time ago. His own groundless uncertainty and fear had ultimately cost Dean his freedom. Castiel blinked away hot tears that started to fill his eyes when he thought about how desolate Dean must have felt that last time his pod came up the coast. Castiel had let him down. He wanted so badly to ask Dean about that last time, but he still couldn’t communicate well and it was probably a bitter and unwanted memory for him. Castiel sighed and pushed all the doubt just under the surface of his thoughts.

He could be there for him now. He could help him and protect him, just as he once promised on that balmy August evening so many years ago.

Castiel slid his hands gently underneath Dean and carefully picked him up. He was surprisingly light and Castiel was grateful for it. He tried to subdue the growing curl of possessiveness he had always associated with Dean. He didn’t want anyone else to touch him, let alone carry him in their arms. Castiel pulled Dean close against his chest when he held him, eyes falling shut in a moment of contentment. Dean buried his wet face in one shoulder and released small, muffled whimpers of subsiding fear into Castiel’s neck.

 _I make him feel safe_. Castiel realized, ashamed to admit how much he liked it.

It was a cruel mockery of the truth. Castiel knew it would take more than an affectionate kiss and a comforting embrace to atone for all the harm unwittingly done. He could start with that, though. He stroked the hair from Dean's face, and brushed his mouth across the side of his temple. Castiel placed a tender kiss to the soft skin there. He could feel Dean lean into him while he fisted the material of Castiel's shirt through trembling fingers. Dean tilted his neck up, and Castiel could see the pulse beating hard in his throat. Castiel traced his fingers lightly along the throbbing skin, while Dean looked up at him with wide eyes. Castiel bent his head and moved his mouth over it, his lips parting so he could suck cautiously at the skin that covered the thrum of a heartbeat. Dean pushed into it. His fingers slowly relaxed. Castiel could feel them gradually release the material he had been clinging to so desperately. Dean made a soft hum of desire. Castiel pulled the skin into his mouth, licking across it while he worshipped Dean’s throat with his lips.

Castiel could feel himself stiffening quickly, so he reluctantly moved his head away and made sure he had a tight hold on Dean when he started to make for the door. Castiel carried him carefully to the tank room, hushing Dean with low sounds of encouragement. Castiel managed to push the door open with a targeted nudge of one shoulder and lifted him up the stairs. He took one step at a time, feeling his way against the steps with his feet, and trying to peer around Dean’s shoulder to make sure he didn't misjudge the reach of his stride. Castiel tipped Dean into the water with a little effort, and he gasped it in while it covered his body. Dean was submerged almost immediately, and Castiel squatted uncomfortably at the top of the steps, inspecting him through the glass with concerned eyes. He watched Dean tumble and roll through the water. The marks and bruises seemed less noticeable through the haze of glass, and Castiel sat back on his heels with a long held sigh of relief.

He left Dean to bathe in the comfort of the water and walked back down the steps to look at the notes Smith had left lying on the counter. Castiel opened the file and flicked through the pages quickly, his eyes scanning some of the words in haste. He needed to find out what Marshall's plans were, so he could do his best to intercept them and protect Dean from suffering any more experimentation. Castiel had almost reached the back pages and was feeling slightly less anxious. There didn’t seem to be much documentation here on what Smith intended to do to Dean. He was about to close the file, when his gaze suddenly fell on two words that caused him to recoil with a gasp. His heart was stuttering as he absorbed the words again, just to be sure he hadn't made a mistake.

“No.” Castiel murmured. His eyes flicked over uneasily to Dean, where he was still swirling through the water. He seemed oblivious to Castiel’s distress. " _God_ , no.” Castiel whispered through a shaky breath, shutting the file with a dull thud. He spread his hands across the counter to balance himself. His head was dipped low, pulling in short gasps of air while Castiel processed the true horror of what he just read.

_____

 


	12. Isolation

**Summary for the Chapter:**

> Castiel makes the decision to enlist some outside help, even though he is reluctant to leave Dean alone. Castiel knows he must return to the point and talk to Shaw about recent events to see if they can find more like him to help set Dean free.

**Isolation**

Castiel reached the reservation by the middle of the afternoon. He was tired and hungry. His hands were still shaking, but none of that really mattered right now. Castiel was terrified of having to leave Dean alone, but knew he had to do something drastic to save him from a dreadful fate. His mind was now clouded by fearful concern that the contents of those files was a portent of what was to come.

_Hybrid Speciation._

Two words that chilled his very blood with the shocking realization of what Smith intended to do. They were going to use Dean, use him in a way Castiel couldn't even bring himself to think about. The implications of such a project were beyond his understanding. Not just as a scientist, but as a human being.

Nobody should play God like that.

Castiel parked up on the curve of the dusty track that wound around the lake, modest single storey houses dotting the banks. Castiel got out the car and tried to see if he could spot Shaw’s truck. He wandered aimlessly for a few more minutes, frustration starting to get the better of him. He made a quiet decision in his head to start asking for news of the other man at nearby residences when he saw a welcome and familiar figure sitting at the very edge of the bank. Achak had his camera in front of his face, fading sun shining brightly when it reflected off the lens. Castiel called his name as soon as he realized it was him, and Shaw turned in surprise. He pushed himself up and hurried towards Castiel. Achak looked relieved and confused at the same time.

“Dr. Milton, how are you?” Shaw said, slinging his camera strap over one shoulder. His black hair fell across his eyes, so he pushed it back when he offered Castiel his hand.

“Hey, Shaw.” Castiel replied, returning the handshake. “Not so good. I need to talk to you. There’s something I need you to help me with.”

“Okay.”

They sat by the edge of the water in silence for a few moments. Shaw was waiting for Castiel to speak again.

“I’m sorry you lost your job.” Castiel began awkwardly. Even though the apology was sincere, Shaw shrugged it off.

“It wasn’t your fault.” Shaw replied. “I expected it anyway, when Smith took over. You know the real reason why I was there. The job wasn’t really that important to me.” He continued. Shaw subtly studied the expression on Castiel’s face with a quick sidelong glance. “I’ve been keeping an eye.” He added wistfully. “When I can. The others, too. I thought they would have left by now, but I think they’re still here. They come and go. It’s pretty isolated up there, but I don’t think they'll stay much longer. Winters can come in cold out here. Too far north.” Shaw seemed to be having a private conversation with himself, rather than telling Castiel anything he hadn't guessed already. “How is he?” Achak asked suddenly. Castiel was grateful for the refreshingly pleasant way in which Shaw acknowledged Dean so respectfully. 

“Fading.” Castiel shook his head. Shaw could see his mouth was set in a fierce line, biting back his emotion. “They're not treating him well… and this morning I learned they're intending to use him for a genetic experiment. It’s not right, it’s just _not right_.” Castiel sighed sadly. He was finding his thoughts difficult to articulate while he felt so exhausted. Physically and mentally. Shaw was perceptive enough to see those deep concerns were built on something other than passing observation. He realized this must be the one Castiel had known as a boy. Shaw hesitated for a moment and narrowed his eyes.

“You care for him.” Achak stated slowly. It wasn't a question. Castiel’s steady expression never changed. His gaze remained fixed on the calm surface of the lake.

“I do.”

Shaw seemed to be looking at Castiel with new perspective. He nodded thoughtfully.

“Good, that may be your strength. Love is a great motivator.”

“I never said I loved him.” Castiel snapped back, pinning Shaw with a blazing glare.

“No. No, you didn’t. Sorry. Let’s call that my mistake, then.” Shaw replied patiently. There was a flicker of understanding reflected in his dark eyes. He was watching Castiel with interest while he twisted his fingers together nervously at the remark.

“I never expected someone I once considered a friend to become so cruel, so ruthless.” Castiel continued. “If only I had known, I never would have put Dean at risk like that.” He stopped suddenly, when he realized the slip.

“Is _that_ what you call him?” Shaw asked quietly. He was starting to make the relevant connections in his head and looking at the man beside him with a new level of appreciation. They both fell silent again for a moment. Castiel couldn't find an appropriate response, so he ignored it completely.

“You know, he calls him an _it_.” Castiel added, with barely contained sadness. Shaw was starting to understand how deeply the level of Dean’s mistreatment was affecting him.

“I'm not exactly a stranger to the ignorance and bigotry of others.” Shaw commented, with a sly smile. “It sort of comes with the territory.” He added, and waved one hand across Great Lake, looking at the small groups of wooden houses that lined the edge of the water. “Pun totally intended.” Castiel gave him a weary smile.

“I’m scared for him.”

Shaw nodded his head back towards the road.

“I know. Come with me. It may be desperate, and probably futile, but I think we should go and see if we might be able to round up a bit of extra support. If you know what I mean.” Shaw winked. It took Castiel a few seconds to register the implication before he nodded. Maybe there was some hope after all.

_____

Dean was turning in small nervous circles in the water since Castiel left, trying hard to distract himself from the ache of empty longing that quickly developed with each minute that passed, and Castiel still hadn't returned. Dean kept pressing his face up against the side of the glass with every stuttered movement and blur of colour that passed by his line of vision. He could hear muffled voices in hushed conversation, and the incessant clicking of unseen machines. The persistent push of waves and sound were loud and disorienting. His senses were being overwhelmed by noise, and it was making him feel nauseous. The hum of the laboratory was intensified by the density of the water and Dean was finding it increasingly difficult to remain calm. He was flexing and tightening his fingers while he tried to steady his heart beat, letting the water wash over the delicate gill slits that lined each side of his neck. They were opening and closing with small, sharp movements that seemed to increase in pace the longer he was alone. He didn’t feel anywhere near safe without Castiel, and Dean had a heavy feeling in the pit of his stomach that his fears were not unfounded.

It was only minutes later, when any faith Dean still had in humanity was completely shattered. He already managed to associate the particular frequency of vibrations with different voices, stilling when he heard one he recognized at once. Dean had no concept of names or hierarchy, but he knew that one, and the very sound of it filled him with dread. He almost stopped moving altogether, buoyed by the gentle lift of the water while it held him up. Dean waited until the noise of conversation seemed to fade before daring to raise his head above the surface. He gasped in a tight breath when he saw someone leaning over the side of the glass, cold gaze fixed on him. Without thinking, Dean opened up his mouth and let out a long high note. It was a distress call. He was trying to signal for Castiel, hoping he was somewhere nearby and would come to help him. His desperate cries went unheard.

_____

“Have you ever _tried_ to communicate with them before?” Castiel asked quietly, watching the side of Shaw’s face while he focused intently on the road stretching out in front of them. A dusty and narrow path down to the sea. Shaw didn’t answer him directly, but Castiel saw him grant a single nod. Castiel waited for a few seconds, but Shaw didn’t explain any further. “Yes?” Castiel prompted, with another sigh. He had no time to skim around the issues just for the sake of pleasantries. There was a persistent fear that kept resurfacing in his mind and making him irritable. Castiel hated leaving Dean alone for so long, not really intending to extend his stay at the point for much longer than he needed in convincing Shaw to help him. Castiel was becoming more and more concerned he seemed to be the only one who still had Dean’s best interests at heart.

_How had it all gone so wrong?_

The thought soon faded when they turned a particularly sharp bend in the road. Castiel reached forward with one hand to steady himself. When he leaned over, he could see the thin line of the coast on the horizon through the dirty windscreen.

“They seemed reluctant at first.” Shaw answered at last, with a pensive expression. “Honestly, I never got too close. I didn’t want to scare them.”

“Of course.” Castiel muttered. He never had the same problem. Dean was always so willing to come to him. So willing to let Castiel touch him. The beautiful recollection of Dean’s body pressed against him was taking over his senses again. Castiel was lost in his memories while the truck continued to bump along the edge of the mainland.

_____

 

_July. 1994._

Castiel woke to contradicting sensations. The soft lull of the ocean and freezing cold feet. He forgot to close the window after coming in from the balcony. Castiel had tried to drown out that one distracting and persistent thought he forced into his mind while he tried to fall asleep. Even with his eyes closed, he could see a hazy image of Dean, the hue of the sea casting reflections on the smooth curves of his shoulders and tinting his skin with a cool blue light. Castiel shifted uncomfortably under the sheets. He could feel the breeze through the window brushing against his toes. His eyes were still heavy with sleep. He eased his body over to lay on his stomach and stalled when he felt the cold, damp spread of something underneath him. Castiel groaned when he realized he must have leaked on the sheets. The erotic dream of Dean moving against him in the water made him very aroused. He shifted again so he could reach one of his hands down between his legs, gently wrapping warm fingers around his developing erection.

Castiel started to stoke light touches slowly up and down the hard shaft while he pictured Dean in his mind. He gave himself over to the pleasure, pretending it was the light caress of tight webbing and long clawed fingers playing up and down his cock. He bit back a muffled grunt of self-indulgence as the image intensified, pace getting faster while he traced the outline of Dean’s lips in his head, and how pretty they would look moving along the length of it. He continued to tug up and down, the sensation of the rising tingle of a budding orgasm starting to well up inside him. Castiel made small thrusts of his hips into his fist, stifling the sounds that wanted to tear out of him when he came. He breathed in deep and steadied his heartbeat, waiting for the blissful feeling to subside.

After a few minutes, Castiel bundled the sheet into a crumpled mass and wiped down his legs and stomach before discarding it on the floor. He pulled on a worn t-shirt and a pair of boxers before making his way out to the balcony so he could shut out the chill of evening. He stepped outside, just leaning forward enough to reach the handle when he stopped. The moonlight was dancing on the surface of the water. Castiel smiled to himself when he heard a soft splash and the distant echo of a long low note that faded away almost imperceptibly. Castiel watched the shifting waves for a few more minutes until the cold bite of night air was too much for his exposed skin. It might have been a trick of the light, or the fact his vision was still marred by sleep, but just for a moment where he expected to see one figure, this time he imagined there were two.

_____

Dean continued to send out short waves of sound in a desperate plea for Castiel to come to him, notes interspersed with fractured attempts at Castiel's name in the only way he could manage. Dean got dragged from the water and pulled forcefully over the edge of the tank. Some small scales were left sticking to the top of the glass and he suddenly landed on his back with a thud. The impact jolted his body, and left him momentarily disoriented. He could feel a strong grip under his arms when he was wrenched up from the floor and carried down the steps.

Dean flinched when he felt a sudden sharp sting at the top of his arm, both eyes growing wide with fear when an all too familiar sensation consumed him. The drug was quickly absorbed into every cell and tissue in his body while he struggled to focus on the small pin-point of light that was flickering above him. The edges started to close in until there was nothing but blackness.

Castiel still hadn't returned.

_____


	13. Unforgivable

**Summary for the Chapter:**

> Castiel still hasn't returned to the institute, and Dean starts to wonder if he really could be implicated in his capture. Dean's memories start to resurface when Smith does a terrible thing to him in Castiel's absence. Dean is finding it difficult to reconcile the love he has for Castiel with the trust that may now be shattered by his inability to protect him.

**Unforgivable**

Dean didn’t realize he was alone at first, when he woke up to a dull ache in the muscle at the top of his arm and a dry itch in the back of his throat. He slowly opened his eyes, blinking with the harsh sting of bright artificial light that streamed out above him. There were no familiar sounds, and the quiet was unusual. Almost eerie in the stark interior of the room he found himself in when his vision cleared.

The constant hum of machines and muted conversations were a continuous disturbance in the background that only served to overwhelm his senses and make him feel sick. In a strange and unexpected way, the calm only felt more threatening. Dean supposed he had been drugged again, even though he didn’t really understand the concept of tranquilizers. He knew enough to realize someone made him black out by sticking something sharp into his skin, presuming it must be something like the darts of sea creatures he often witnessed snaring prey in the deeper parts of the ocean. Dean let the memory go. His thoughts were hazy and indistinct, still fighting a desire to throw up.

His scales felt cold and dry to the touch. Dean realized he couldn't move the lower half of his body at all. He attempted to turn, trying to smooth his fingers along the seam of his tail where he could feel some of his skin starting to flake off as a result of so much dry heat permeating the laboratory. His heart rate started to increase when a curl of panic welled up inside him. Dean twisted his head round and could see his surroundings were different again. There was no water for him, and many unfamiliar metal objects lining the counter. Dean didn't want to think too much about what they planned to do to him next. He tried to ignore the warning glance Castiel had given him before he left. The look in Castiel's eyes still haunted him, and Dean wondered what exactly he might have done wrong to make him leave so suddenly. Dean had no idea how long he was unconscious and started to feel a treacherous stab of betrayal. Not only had Castiel left him alone when he needed him, but he hadn't answered his call. 

Dean pushed away the terrible thought Castiel wouldn't be coming back, or he might never see him again. Dean could feel a sting at the corners of his eyes. He always tried to pretend the warmth running through his blood when he used to lay with Castiel on the beach during his breeding cycle was just a response to his heat. He could never explain to Castiel that he thought about him as a potential mate. They were different. Castiel probably didn’t feel the same, and Dean had been so frightened of scaring him away. He had loved Castiel since he was a boy, and now he had left him forever. Left him alone to be humiliated and abused. Dean swallowed down a sob, turning his face away from the light. He closed his eyes, mind still clouded by the last traces of the drug flowing through his system when he thought back to the last time he went to meet Castiel by the beach house. His tears flowed freely as the pain of that memory burned away all hope, and twisted inside his stomach. The long forgotten feeling of abandonment suddenly resurfaced, curling a cold grip around his heart.

 _____

 

_September. 2004._

The boy was late this year. Dean tried to dampen down the growing thread of doubt that kept filling his mind with every new day that dawned and the shore stayed empty. He was in his second cycle of heat and was going to tell Castiel this time he had chosen him. Dean was a man now. He was allowed to make his own decisions and let his senses guide him. His brother and mate spent their summers at one of the bays further north. They liked the privacy of the remote caves they once discovered, and the area was often provided a warm tide that sometimes wound its way through the small inlets and islands that were dotted along the coastline. They were almost ready to start a family, and would need somewhere safe to raise their young.

Dean first visited the harbour weeks before he expected Castiel and his family to arrive. He couldn't wait any longer. Dean had missed the boy from the house on the beach, with his beautiful eyes that were the colour of the sea, and his plump pink lips that Dean would remember forever. The last time they had been together, Castiel promised to return to him. Dean had left Castiel standing on the sand, saying goodbye with a simple wave of his hand and a twist of his tail. The years since had passed slowly. Eventually the time came for Dean to return and claim Castiel, if he would have him.

Castiel didn't come.

Dean didn't see him that summer, so he had no chance to make his claim that season. He left it until the last possible moment to return to the pod before they moved south into the warmer waters for the cold months, and Castiel still hadn't returned. The ache in his heart at the loss had taken a long time to fade. It had never gone completely, and Dean didn't really understand why the boy never came back for him as a man. They made a promise to each other.

It had been unspoken. Maybe that was why Castiel hadn't felt bound by it. Dean would have to wait another cycle before he could return, and there was no guarantee Castiel would ever come back to the harbour.

 _He_ would return. Dean would always return, in the hope one day Castiel would be there to meet him. He didn't care how long it took. Castiel was the one Dean wanted, and there was nothing anyone in his pod could do to dissuade him. He loved Castiel. He just needed to tell him.

_____

Dean was on the edge of sleep again when he heard the door click, watching the white blur of a lab coat pass him by. The person Dean feared most suddenly appeared in his space and pressed his face uncomfortably close. Dean wanted to understand exactly what it was about this man who filled him with fear and loathing. Castiel clearly knew him, and Dean had formed some connection the men must work together. He made the relevant links between the fact they were in an examination room, and that Castiel may have had something to do with his capture. Dean couldn’t shake the horrible implication maybe the man he wanted more than anything else in the world had led them to where he would be waiting.

Dean pushed the thought away. He couldn’t stand the idea Castiel had betrayed him. It couldn’t be true. He once believed Castiel really cared for him. He looked so sad when he first saw Dean through the glass wall of the tank, but Dean couldn’t be sure of anything anymore. This world was strange and confusing, and he didn’t like it. He longed to go back to the water.

Smith poked Dean hard in the chest with the end of his finger to make sure he was awake. He needed him to be conscious for what he had planned for him while Castiel wasn't there. His now former friend was really starting to piss him off with his constant attempts to try and comfort the creature he captured. Castiel was distracting him from the genetic project he had planned for it.

Smith had developed a cruel and merciless streak to his personality he never really expected. Marshall knew he had become a monster but he didn’t care anymore. Castiel was once a good friend, but he was becoming dangerous. His attachment to this animal was causing him to make reckless decisions that could jeopardize his experiment, and Smith wasn't going to allow it. He needed a DNA sample.

Castiel was unexpectedly missing from Dean’s tank room, and Marshall made an impulsive decision to take it there and then before Milton had the chance to make any complaints. Smith remembered how sexually responsive Dean had been in the laboratory downstairs when they had accidentally stimulated him. Smith had absolutely no idea Dean was in heat, no concept of mermaid mating cycles. Dean had no intention of enlightening him.

Dean shifted nervously against the restraints when Smith leaned into his space. He could feel the unpleasant brush of warm breath against his cheek, consciously thinking how different it felt when Castiel’s mouth was close. Dean spent years regretting he had never shown Castiel how much he wanted to stay with him. Castiel never learned much about Dean and his pod, or made the connection between how much passion Dean had put into those deep kisses when they moved against each other on the sand. Castiel hadn't seen or scented the thick slick Dean released into the water when Castiel aroused him. Dean kept the line of his tail at the very edge of the waves, and the heady pheromone dripped into the foam and was quickly absorbed into the dry sand at the edge of the water.

Smith examined Dean with rough, probing fingers. His hand went straight for the round bulge at the front of Dean's tail, almost constantly swollen while he was ready to breed. The scientists just presumed his base instincts were easily stimulated. They could never hope to understand the complications of his species, or how they would claim just one true mate. Dean was intelligent and sentient, and he was being treated like a caged beast. Castiel had seen it. The humanity reflected in those lonely green eyes that day at Winter Harbour when Dean dared to come close and press their lips together.

Dean was lying as still as he could while he watched the movement of people surround his line of vision. He hated being strapped down and having to stay forcibly pinned against a cold surface while men moved around his body. Dean could feel the burning gaze of Smith’s eyes against the side of his face when he tried to block out all the noise. Smith didn’t lean away and Dean knew he was studying the contours of his body. Dean didn’t think that man cared whether he hurt him or not, knowing Smith didn't view him in the same way Castiel did. It chilled his blood. Smith set about attaching instruments to Dean while he moved around him, clinically detached from the needs of the man who was unwillingly held fast beneath him. Dean couldn’t see much from his position, but he could feel Smith’s fingers pawing at his groin and trying to release his hard penis from beneath the protective cover of shiny scales.

Dean let out a small whimper when it was pulled free, feeling the sting of something cold and tight around him. He was already overly sensitive because of his heat, but Smith presumed Dean was getting aroused by the contact of the machine he just attached to him. Dean saw another figure in white approach the bed from the corner of one misty eye. Dean caught the tones of a muffled voice next to his side.

“How are you going to get the sample?”

Dean didn’t understand all the words, but he knew it had something to do with him and he was scared. The tight clamp around his dick was making him very nervous, gaze slipping to the door in the vain hope he would see the man he loved come bursting in and rescue him from this horrible torment. Dean needed Castiel so badly, he could almost feel it as physical pain.

“I’m going to milk it out.” Smith replied, in an unnaturally cold voice. “It's already over-stimulated. I don’t think it'll be very difficult to get it to ejaculate.” Dean heard a quiet gasp of breath at his side. He didn’t recognize the voice, or remember seeing him before.

“You can’t do that, it breaches the Harvard contract.”

The words were just disjointed washes of noise Dean couldn't understand. His eyes flicked hesitantly between the two men who were standing over him.

_Castiel._

Dean wanted him so desperately. He didn’t even know if Castiel had any intention of coming back, and it left him cold.

“Well.” Smith answered, with a sardonic smile. “I don’t really think I need to be worried it's going to report me to the council.” The man Dean didn’t know looked uncomfortable. He was studying Dean, deep lines of apprehension forming on his face.

“I can't be a part of this. It goes against everything we believe in. What exactly are you trying to do?" The soft lull of the unfamiliar voice continued. Dean stared at the blank ceiling and tried not to breathe too hard in case it gave away his fear.

“I'm making history, you fucking idiot.” Smith yelled back at him, roughly adjusting the cylinder encasing Dean’s penis. Smith turned it on, and the cold machine started to manipulate the delicate and already over-sensitive skin that covered Dean’s cock.

There was a chilling light reflected in those dark eyes when Smith continued to examine the brutal, regular ministrations of the machine while it quickly brought Dean to orgasm. He fought it for as long as he could but it only delayed the inevitable. Dean shook and trembled as he came, his semen splattering the insides of the container Smith attached to him. Dean closed his eyes and forced the overwhelming pleasure to subside. He breathed deep and tried to steady his heartbeat. Smith detached the machine and shook the tube while he examined the contents. Dean was still making small and uncoordinated thrusts, attempting to push away the feeling that had consumed him when Smith collected his sample. It was disgusting, violating. Dean couldn't detach from the dreadful realization something so intimate had been taken from him without his consent. Dean hoped no one would notice the pool of aromatic chemical leaking from between his scales when he succumbed to the artificial pleasure forced upon his body.

Dean willed Castiel to come back with everything he had. All he wanted was for Castiel to hold him, tell him everything was going to be alright. That he loved him.

That he came back for him.

He hadn't.

Castiel left Dean alone on the soft cold sands of Winter Harbour, their promise lying broken and discarded on the featureless wooden steps of the beach house.

Castiel had abandoned him then, just as surely as he'd abandoned him now.

He was alone.

_____


	14. Stay

**Summary for the Chapter:**

> Dean almost gives up hope of ever seeing Castiel again, and a deep sadness starts to overwhelm him. Castiel believed he had no choice but to leave Dean alone in the search for someone just like him. Castiel wants to get back to Dean and show him this time he came back for him.

**Stay**

Castiel waited on the path winding down to the sea while Shaw disappeared behind one of the dunes. Castiel watched the long tufts of marsh grass move gently in a breeze rushing in from the sea. He still couldn't shake the feeling of restlessness under his skin at the thought he had left Dean all alone. Castiel felt so torn. He wanted to stay with Dean and keep him safe, but knew he couldn't hope to fight this alone. He consoled himself that at least he had one ally in Shaw, and Castiel's confidence in him was growing. Shaw knew the other creatures. He may not have the same connection with them Castiel had with Dean, but it was something.

Shaw told him to wait for the signal before coming down to the shore to meet him. The journey had not been uneventful. Castiel learned Shaw tried to make regular contact with them, believing he may have gained a small measure of their trust. Castiel wondered if they knew Dean, or even if they were in the same pod. He was hoping beyond hope they would help. Castiel had no idea how they would explain what happened, but he was more than willing to try. He owed Dean that at the least. Castiel wanted Dean to understand the deep regret that still haunted him, shaping the way he lived his life for the last twenty years. Castiel had lost his way. He hadn't realized quite how much until he saw Dean again. It was the loss of _him_ that made him feel so hopeless in the years following their parting. Castiel denied it, pushing it into a dark corner of his mind. He spent decades searching for something, anything, to distract him and fill the void in his heart that had been carved deep when he watched Dean swim away that fateful summer.

Castiel had found him again. They had found each other. That was all that mattered now. Everything he had overcome, everything he worked for was meaningless and empty without him. His mind was finally clearer now when he pictured Dean in his head. His beautiful face framing the deepest green eyes Castiel had ever seen. He smiled.

His thoughts were suddenly broken when he heard Shaw whistle across the sand. Castiel's eyes snapped up, searching the vast stretch of deserted beach. He started to descend the steep precipice to meet Shaw at the bottom of the slope. A smile was spread wide across Achak's face when he lifted up one hand in greeting. Castiel’s expression was a mixture of hope and anticipation while he waited for Shaw to call him down. He eventually nodded, beckoning Castiel to follow with a quick flick of his fingers. Castiel stayed close while they walked slowly towards the dark recess in the side of the cliff where a small branch of the ocean trickled in between the stones and deposited eroded pebbles at the entrance. As soon as they reached the cove, Castiel could hear the low murmur of a familiar resonance echoing off the walls. It made him think of Dean. He could hear the vibrations when waves of sound drifted through the opening as they approached. Castiel held a breath, edging inside the small hollow. He could see the two figures much better now as more light filtered through the small cracks in the stone.

They were both immersed in the shallow water of a pool that opened up at the back of the cave. Castiel was trying not to breathe too loudly while he watched them in amazement. Shaw was further forward, and they seemed to be fully aware of his presence. Neither of them seemed disturbed by it and they were clearly familiar with him. Shaw looked at Castiel over his shoulder, giving him a gentle nod of confirmation it was alright to draw in closer. Castiel picked his way over the slippery stones lining the stream where it ran almost silently through the middle of the dark chamber. One of the figures swam closer to the edge, seeming to acknowledge Shaw with a simple wave of his hand. It was a decidedly human gesture he appeared to have picked up. Castiel felt a warm flood of emotion when he remembered how he had taught it to Dean when they were children. He wondered distractedly if the mermaid had picked it up from Shaw, or from Dean. It was an encouraging thought. Maybe they did know Dean after all. The ocean was vast and deep, though. It was too much to hope they would be familiar with Dean and his pod. Castiel tried to push down a rising surge of disappointment when he contemplated the sheer scale of it.

Castiel watched Shaw kneel down beside the water, cautiously reaching one hand into the inside pocket of his jacket. Castiel couldn’t really see what he was holding, but he saw a glint of light reflect off a small shiny object. It must have been made of metal. Shaw placed it on one of the larger flat rocks that was almost level with the man’s chest. He presumed it was probably a small token of friendship crafted for that very purpose. Castiel thought it was a very humble and thoughtful gesture. Shaw had a much greater depth to his personality than Castiel gave him credit for. They spent some time in the still and almost silent safety of the hollow in the cliff side. Castiel held back and just left Shaw to try and communicate with them. He was patient and calm while the merman struggled to understand events that caused him to search them out, to plead for their help to save Dean.

Shaw seemed much more confident than Castiel when they left that afternoon. Shaw reassured him there had been some exchange between them, and promised to return in a few days. Castiel wasn’t really listening to what Shaw was saying on the drive back to the institute. He heard random snatches of conversation, murmured encouragements he believed in them. The male one particularly seemed to place some significance on the mention of Dean. It was only the name Castiel called him when they were young, but Shaw's description of him seemed to stir something of interest.

Castiel's eyes were fixed on the road while they moved along, thoughts once again consumed with getting back and making sure Dean was safe. He should never have left him again. Castiel just wanted to try and help. All he ever wanted was for Dean to be happy, to be free.

_____

Castiel ran up the main steps as fast as he could, heart beating wildly in his chest when an intense desire started to flood over him. He couldn’t be sure if it was the effects of adrenaline still coursing through his system, or the intoxicating sensation of being able to see Dean again. All he wanted to do was touch him. Castiel longed to show Dean he came back to him.

Castiel hurried up the corridor, breaths coming fast and shallow when he neared the end of the hallway. He could see the door to the tank room was slightly open, and Castiel could hear the sound of languid splashing over the monotonous, repetitive click of machines. There was no one else there, and Castiel entered quietly so as not to scare him. His heart broke when he saw Dean lying on his back on the surface of the water. He looked so sad. His arms were floating uselessly by his sides, tail almost completely curled in on itself. His pale face was turned towards the small chink of sunlight filtering in through the blind. Dean's gaze seemed to be fixed on it. The water was cloudy, discarded remnants of half-eaten fish littered in one corner.

Castiel felt horribly sick while he quickly shed his jacket, dropping his pack on the floor. Castiel rushed over to the side of the tank and climbed the steps while he shouted his name. Dean didn’t seem to hear him at first. He was lost, wandering alone in some dark place in his imagination. Castiel had to call him three times before he even flinched. Dean twisted all the way around before slowly unfurling his tail, looking across the edge of the glass at Castiel with wide green eyes. For a moment it looked like he wasn’t even sure Castiel was real. Dean hesitated as they stared at each other, holding his breath with his gills pressed flat against his neck.

Dean suddenly launched his entire body across the top of the water, wrapping himself around Castiel with so much force he almost lost his balance. Dean was grabbing recklessly for Castiel, pulling him in close while he peppered hot, determined kisses all over Castiel's face. Castiel held him up while Dean moved his mouth along the line of his cheeks, dotting small hurried pecks over the bare skin of his exposed throat. They were desperate and passionate, and Castiel realized just how much Dean had missed him. Castiel leaned into him and gently touched their foreheads together, both inhaling fast gasps of air when Castiel slipped his arms around the base of Dean’s back. It felt like they were breathing each other in. Dean’s skin felt cold and damp under his fingertips when Castiel's hands moved lower, splaying wide to caress the smooth rise of his tail. He could feel Dean trembling, and Castiel wasn’t really sure why. It could have been from excitement or fear. Maybe even from desire. Castiel pushed down the selfish hope it was the last one.

Dean was still draped over Castiel’s shoulders when their breathing slowed, eventually relaxing a little under his hands where Castiel held him, trying to coax him over the ledge. He knew Dean must be uncomfortable, pushing up so close against Castiel, the hard tank edge was digging into the soft skin of his stomach. Castiel wanted to get him out and hold him without the barrier of glass between them. Castiel pulled Dean gently over the side, sitting down heavily on top of the steps while he cradled Dean in his arms. Castiel ran his hands along the tail, searching for any marks or signs of mistreatment. He stilled when he reached the lighter ridge of scales running across the line that joined his tail to his stomach. Dean recoiled, and Castiel thought he heard him inhale a sharp breath when he dipped his head even lower. Dean let out a small cry that vibrated into Castiel’s shoulder.

“Dean? What happened? What did he do to you?” Castiel whispered into his neck. He knew Dean couldn’t understand all he was saying, but Castiel hoped the soft questioning tone of his voice would mean something to him. There was no response, so Castiel leaned his head back and took Dean’s face in his hands. “Dean?” Castiel prompted again, dropping his gaze to study the delicate patch covering Dean's groin. He gasped when he noticed some dislodged and damaged scales that seemed to have been scratched away from the surface. There was also a deep, raw imprint in the shape of a circle where the machine had been forced roughly into the skin. Castiel just stared at it in dismay. He wasn't sure what that mark might imply, but it was clear Dean had been the victim of something dreadful Castiel couldn't even bear to think about. He just pulled Dean in closer, brushing calming strokes through his hair while he hushed him.

Castiel struggled to his feet and carried Dean down the steps. He had to get him free of that room for now. Castiel was suspicious no one else appeared to even be in that section of the building. He didn’t think Smith would have left Dean unguarded unless he had no cause to be concerned he might get out. Marshall clearly didn't care about the need to make sure Dean was clean and safe. Castiel warned him Dean would get sick if he was neglected, but he had apparently paid no heed. Castiel felt a sudden and overwhelming compulsion to take Dean and lock him away from the rest of the world so he could just own him, protect him. Without any heed for the consequences, Castiel hauled Dean up even further and pushed the top of his body over one shoulder. He wrapped one arm around the middle of his tail and held Dean close while he carried him through the door and down the hallway. Dean was so still and quiet, Castiel could feel a developing surge of alarm rise up from his stomach. He didn't know what had happened, but whatever it was had clearly upset him. Dean was completely motionless while Castiel moved quickly down the hallway towards the bunk house. It was a small room right at the back of the top floor set up as a modest living area. Sometimes they would get caught up in an investigation or come back late at night from a field trip, so they installed a room to accommodate anyone who might want to stay in the building overnight.

Castiel had only stayed in it a couple of times and knew it was usually empty, so he didn’t have too much concern anyone would be there. Castiel pushed open the door and made straight for the alcove at the back. He gently set Dean down on the soft bed in one corner. When Dean’s head touched the unfamiliar softness of the pillow, his eyes flickered open once more, looking up at Castiel with confusion. Castiel edged him over a little and sat down next to him, helping Dean to straighten out his tail and ease him onto his side to get him more comfortable. Castiel ran his hand longingly over the bare skin of Dean's arm where it rested limply on top of the sheet, before kicking off his boots and pulling his legs up on the bed. He curled them up until his knees were pressed close against the front of Dean’s tail. He was perfectly in line with him. Castiel rested his head on one hand, surveying Dean’s face with sympathetic understanding. Castiel touched his cheek affectionately.

“Stay here. Stay and rest. I'll watch over you.”

Dean was looking up into Castiel’s eyes. He didn’t seem to want to smile. There was something reflecting back at him like lingering hesitation. Dean had no reason to doubt him now. Castiel _had_ returned. He wanted to show Dean how much he cared for him. Dean pushed himself up, struggling to lift the top half of his body from the bed. Castiel helped him to lean up, thoughtfully placing another pillow behind his back to support him. Dean picked up on that one word. It reminded him of their past and how much he wanted to say it the last time they were together. Dean tentatively reached forward and pulled Castiel’s hand towards him, spreading it across his chest in the space that covered his heart. Dean forced his voice to form sounds Castiel could understand. 

“S t a y.” Dean echoed. “Cas… _stay_.”

Castiel felt his heart ache. He could never refuse Dean anything. Something he discovered and accepted a long time ago. Castiel had no intention of leaving Dean again. He closed his eyes, melting into the touch where his hand still rested on Dean’s chest. Castiel could feel the pulse of Dean's heartbeat underneath his palm, and the soft rise and fall of unsteady breaths. Castiel leaned forward a little more, sealing his lips against Dean’s open and deliciously wet mouth. He whispered the response into his kiss.

“Yes, Dean. I will stay.”

_____


	15. Heart

**Summary for the Chapter:**

> Castiel is finally alone with Dean, but must take on a new and unexpected challenge to be able to stay with him. A sudden change of focus allows them to spend more time together but there are conditions which must be obeyed if he is to keep Dean safe. Castiel decides he can no longer deny the love kept locked away in his heart for all the years that have passed since their first meeting.

**Heart**

Castiel reluctantly pulled his mouth away, and slowly opened his eyes. Dean looked so beautiful. His eyes had fluttered shut again when Castiel pushed a kiss to his lips and made a promise to stay with him. Castiel could still taste him. Dean’s mouth was slightly open, the movement of their tongues as they slid together stirring something deep inside his heart that had never been forgotten. Dean longed to tell Castiel he wanted to claim him as his mate.

Castiel knew something frightened Dean, and the implications of it sent a cold warning flooding over his senses. Castiel remembered how independent and strong Dean was when they were children. He deliberately didn't push Dean to explain what happened in his absence, daring a small and hesitant glance at the marks scarring the front of his tail. The bruising was starting to discolour some of the lighter scales, the damage forming a line running down from his stomach. Castiel had a desire to hold and comfort him. He really wanted to stay. Dean seemed unnaturally quiet when Castiel carried him away from the tank room. The possessive desperation of those kisses when Castiel returned was something unexpected and wonderful. Castiel knew it was a way of showing him how glad Dean was he came back for him, often finding their own way to communicate when they were together. Words never seemed very important. The long years had passed slowly since their parting on the shoreline that day. Something had been left unsaid. A small word or phrase that had so much more meaning to it than could ever be contained within a few simple letters. Castiel never knew how much Dean wanted him to stay at the beach house forever, and already made the decision in his head he would find a way to tell Castiel this time. Dean could feel the soft warm breaths on his cheek, almost hear Castiel’s blood rushing through his body. He suddenly felt very sleepy.

Dean’s eyes stayed closed while Castiel stroked the skin along his arm. Dean shivered at the touch, but his breaths gradually evened out and he curled the end of his tail around Castiel’s legs when he relaxed. Castiel edged his knees up a little further, pulling Dean into him. Dean made a small, startled noise when he settled on the pillow and Castiel carefully pulled his arm out from under him where it had become trapped beneath his body and the bed. Castiel rested his head on Dean's chest, listening to his breath coming in laboured gasps while he let Castiel hold him. Dean was asleep within a few minutes. Castiel draped a sheet over his tail and tucked it carefully around the lower fin, mindful not to catch any of the delicate scales. Castiel watched Dean for a long time before he too felt his eyes growing heavy and drifted into a fitful sleep, both arms wrapped around Dean’s body with only a small space between them.

_____

Castiel was suddenly aware of an indistinct wash of noise that seemed to escalate in pitch as his senses gradually returned. He stretched out a little, subconsciously tightening his hold on Dean where he was still asleep and dreaming next to him. It was the first time since he had been confined to the institute Dean even felt half-way safe. His arms were folded up between their bodies, and his head had slipped down to rest in the dip of Castiel’s shoulder. Dean had a look of calm peace on his face, breathing slow and regular. Castiel still had his eyes closed while the background sounds filtered in and out of his thoughts until he heard someone shout him out of his slumber. Castiel turned his head towards the door to see Smith and one of his researchers staring at him in disbelief.

Castiel was fully awake within seconds, heart beating impossibly fast when he pulled away from Dean and scrambled off the bed. He hurriedly tucked in his shirt and ran his fingers roughly through his hair in a futile attempt to pretend he hadn't just fallen asleep on the bed with a merman in his arms. Castiel stopped dead when he realized it was pointless trying to deny it. He was caught, first thoughts filled with the fear he had put Dean at risk again. Castiel couldn’t seem to control his emotions around him. There had always been a dangerous and distracting edge to Dean’s presence that made Castiel forget himself.

“What the fucking hell are you doing?” Marshall gasped after a few seconds. His face was etched with something bordering on utter confusion, nose screwed up in distaste at what he just walked in on. Castiel could feel his cheeks burning while he stammered to explain. Dean started to stir on the bed, and Castiel could hear the rustle of dry scales as they moved when he stretched out his tail. Dean let out a soft moan, beginning to open his eyes. Castiel backed away, protectively placing his body between Dean and the threat standing in the doorway.

“I... er... his tank needed cleaning.” Castiel murmured faintly. He was blinking rapidly, trying desperately to think of something more appropriate to say. Smith’s expression changed into something accusatory and unpleasant. “I thought he was going to get sick, so I brought him up here to lie down.” Castiel continued. The room was quiet, but the air still seemed to press in too close. Castiel could feel the tips of his fingers digging into his palms while he held his breath and waited. Smith looked between them and seemed to consider something for a moment. He narrowed his eyes and pressed his lips tightly together, making a stilted hum at the back of his throat, and watching Dean closely when he propped himself up on the bed. He was looking up at Marshall with fear in wide green eyes. Smith took a purposeful step towards Castiel and leaned in uncomfortably close. Something seemed to have suddenly clicked in his head, the look in those dark eyes making Castiel feel more uneasy than he had in days.

“I'm not sure that's entirely true.” Smith whispered, almost too quietly into Castiel’s ear with a self-satisfied smirk hanging on his lips. He was beginning to realize there was something much deeper than just their apparent physical need to be near each other. Dean was shifting nervously under the sheet Castiel wrapped over his tail to stop him from shivering. Castiel was torn between trying to reach for Dean and defiantly meeting the searching gaze of the man who was standing next to him. “Castiel.” That one spoken word was loaded with a calculated coldness that filled him with dread. “I'm not sure what's really going on here, but I can see how well it responds to you.”

Castiel swallowed hard, refusing to let the words come. He couldn’t risk antagonizing Marshall any further. He was only grateful Dean couldn’t understand what he was saying. Castiel knew it would have hurt him. He didn’t want Dean to think he was being condemned as anything less than captivating. Castiel hardly dared to take a breath while he wondered what that was meant to imply. He didn’t trust Marshall anymore, and his sudden change of direction was more likely to be self-serving in some twisted way. It actually made Castiel more anxious than when Smith was threatening to harm him.

“Okay.” Castiel attempted, studying the other man's face with a suspicion the conversation was definitely not over. Smith’s mouth started to curve up at one corner, and Castiel knew he was trying to conceal some malicious intent behind an unpleasant smile.

“I want you to teach it.”

Castiel frowned.

“Sorry?”

“Teach it, Castiel. It likes you.” Smith hesitated, giving Dean a token look of displeasure. “Rather too much I suspect, but I can probably use that to our advantage.”

“Your advantage, not mine.” Castiel replied blankly. He wasn't sure what Smith was hoping to achieve by allowing them to spend more time together, but he was certain it probably wouldn't be for anything good and spared another tentative glance at Dean where he was watching the exchange from the bed. Castiel knew Dean was trying to catch odd words he remembered from before. Lines were etched into his brow where he was concentrating too hard. “What exactly do you want me to do?”

“It would be a lot easier if it understood me.” Smith nodded thoughtfully, like he was debating a private thought in his mind. “Teach it how to be human, Castiel. That’s what I want.” He finished decisively, finally pulling back. Castiel sighed and turned away, desperate to get back to Dean. Smith suddenly reached for Castiel to wrap one hand firmly around his arm. The cold glint in Smith's eyes returned, just for a moment. “If you try anything, Milton, anything at all.” Smith added. “I'll break your little boy toy - and make you watch.”

Castiel inhaled a sharp gasp, fixing his gaze on Marshall’s back when he walked out into the corridor.

_____

Castiel moved Dean into the bunk house that afternoon. He was trying hard to suppress a feeling of warm excitement that kept threatening to spill out when he thought about all the precious time he would be able to spend with Dean, and keep him safe. Castiel knew it wouldn’t last forever, and Smith had other plans for Dean but Castiel was going to take this while he could. He arranged for a smaller, clean tank to be installed in the main room so they could stay there together. Castiel was still anxious about leaving Dean alone. He kept thinking about the horrible image of the discoloured, raw scales so obvious over his groin. Castiel hadn't mistaken the words on that file. There was something dark and unnatural about it, and he couldn’t shake the fear it was far from being over.

Dean seemed so much happier now they were alone, making small humming sounds in his throat every time Castiel came near the side of the tank while he moved around the apartment. His blue eyes kept flicking over to Dean while he rearranged the living area, pushing some of the furniture to the edges of the room so it would be easier for him to walk around. Castiel smiled to himself at the little splashes Dean kept sending out to get his attention. When he had put everything away, Castiel walked over to the edge of the glass and held out his arms. Dean immediately pushed himself up on the palms of his hands and tipped his body over the side. He fell into Castiel’s embrace. Castiel carried him over to the couch where he left some towels to soak up any excess moisture from Dean's skin while he dried off.

They lay together for a while. Castiel remembered the way he tried to teach Dean words before, drawing letters in the sand with his finger and making up little pictures that meant a place or the meaning of a sentence. Dean had been good at those. His voice still struggled to form a lot of the more complex sounds, but he understood most of what Castiel attempted while they stretched out together in front of the fire. Dean had tried really hard to say Castiel’s name again, but he always got stuck on the syllables at the end. Castiel smiled when he curled his hand into a fist and pressed it against his chest.

“Me. Me. Castiel.” He repeated, encouraging Dean to watch the way his mouth formed the shape of the word. Dean stared into his eyes for a long time before he reached his own hand forward and covered it over the space where Castiel had rested his own. He knew Dean could feel the pulse of his heartbeat under the touch. “That’s my heart. Heart.” Castiel explained patiently. Dean tried to copy the word, pressing his open hand over it with a small smile.

“Me. H e a r t.” It was shaky and mispronounced, but the meaning was clear. Castiel could no longer deny the sensations spreading through his body whenever Dean touched him. Castiel nodded.

“Yes, Dean. You’re my heart.”

_____


	16. Claim

**Summary for the Chapter:**

> Castiel starts to recall some forgotten memories of the last summer he spent with Dean. The bond they share is tested when Dean makes his claim. Castiel finally realizes Dean wants him as a mate, but there is too much love there to betray the trust Dean has in him. Castiel refuses to take advantage of Dean while he is still so scared and desperate. Dean mistakes his loyalty for rejection.

**Claim**

_July. 1994._

Castiel couldn't be sure how long Dean waited in the shallows while he watched him from the balcony that night. Castiel could hardly believe how much he already wanted to be with Dean again. They only said goodbye a few hours before, but the sight of Dean's long body stretched out in the waves caused something to rise up through Castiel's chest and tug relentlessly at his resolve to remain in the beach house. It was all Castiel could do to stop himself leaping from the second floor and running down the sand to hold Dean in his arms once more. When he looked out across the bay, Castiel realized he hadn't been mistaken. There was another mermaid swimming and diving through the dark surf a few metres out from shore. It was definitely a male by the contours of his upper body just visible in the soft reflective shimmer of the moon where it bathed the surface of the water with light. Dean seemed almost oblivious to the presence while he rolled with the tide, sea crashing against the sand and sending up silent sprays of grey foam. It all looked so different in the darkness. There was a dull wash of colour where everything had been so bright and clear in the early evening when they parted. Castiel could feel his cheeks heat up when he remembered what he did to himself earlier, imagining Dean’s mouth on him. He felt another twitch of arousal between his legs, consciously fighting against the desire to reach down and play with it again. Castiel leaned forward and rested his elbows on the edge of the terrace. The breeze from the sea was cold without the sunlight to warm him, but he couldn’t seem to pull himself away. Castiel rested his head in his hands and gazed out across the ocean. He knew Dean didn't know he was watching him, or had any idea his eyes were fixed on the smooth contours of his chest and the line of his beautifully crafted tail while he played in the water. It almost looked like he was basking.

Castiel watched Dean for a long time until his eyes started to close, knowing he needed sleep. He reluctantly moved away from the edge and reached for the door before taking one last lingering glance at Dean. Castiel gasped when he realized the other creature had joined Dean in the shallows while Castiel was distracted. He could hear the indistinct sounds of unintelligible conversation when Dean suddenly raised one of his arms and pointed up towards the beach house. Castiel leaned into the shadow of the doorway in a hollow effort to conceal himself from view. He could feel his heart beating fast in his chest when he realized what Dean was doing. Castiel peered out from behind the door frame. Both were now staring up at his window. Castiel hurriedly pulled the door shut and got back into bed. He dragged the sheets up and wondered what exactly it was Dean had said about him, or why he would share their secret with anyone. It must have been someone close to him. Castiel was tempted to go down, but he didn’t want to frighten them by appearing on the beach in the middle of the night. There was something very intimate about the way they were chasing the waves together. Castiel imagined they might even be brothers.

_____

Castiel was watching Dean closely while he moved against his hand. How could he have forgotten? The images were slowly fading back into focus. Castiel pulled at a beautiful memory of the last summer he spent with Dean. Castiel knew there were more of them. He had seen Dean with his pod, his family. Castiel had blanked out many painful memories over the years, but this was a happy one and he couldn’t understand why he hadn't remembered it until now. Castiel was leaning into the touch, while he replayed fractured images of that night in his mind. Dean was so close, so warm. His skin was flushed by the glow of the small fire Castiel had set in the small log burner in the centre of the room. The winters could come in cold on the coast. They stayed like that for several long minutes while Castiel allowed himself to appreciate just how truly exquisite Dean really was. There had been a time when Castiel appreciated him as an amazing creation of nature, but now there was something much deeper and more possessive about the way he admired the graceful line of Dean's body, and the lure of his eyes. Castiel was completely enraptured by the way every muscle pulled tight under Dean's skin whenever he was next to him. Their closeness seemed to effect Dean very much, and Castiel wasn't even ashamed anymore that Dean made his heart beat faster in his chest. Another surge of warmth ran through him and pushed down into his groin. Dean’s tail was twitching lightly over Castiel’s feet while he stroked the space over his heart with long delicate fingers. Dean had always been so careful when he touched Castiel, but now they were alone Dean seemed unusually eager to run his hands roughly over every curve. He accidentally scratched the soft skin as he dipped his fingertips under the edge of Castiel's shirt where the buttons were undone. Castiel let out a small gasp when Dean drew blood. There was no pain. Castiel was more surprised by Dean’s sudden need to want to touch every part of him that was open and exposed.

Castiel started to run his hands over Dean’s back, gradually moving the caress forward until he dared to rest his hands on the round swelling at the front of his tail. The scales were thicker there, and surprisingly smooth under his fingertips. Castiel suddenly stopped, and rubbed the ends of his fingers together. He could feel the tacky sensation of something thick and slippery under his touch when he moved the strokes along Dean's body. Castiel could feel Dean tense when he inspected it with searching fingers. When Castiel pulled away he could see Dean had dipped his head low in a shy gesture, eyes almost closed. Castiel lifted his hand up to examine it where slick coated his fingers, frowning with confusion when he realized it must have come from Dean. He had no idea what it was. A terrible stray thought gripped Castiel cold when he presumed it was blood. Castiel squinted in the firelight, letting a breath of relief pass through his lips when he saw his fingers weren't stained red. Castiel brought his hand up closer, inhaling the potent scent from the mysterious substance before it had even reached his face. There was something about the way it seemed to draw him in. It had a subtle hint of musky amber wood and it was intoxicating. Castiel breathed deep to pull in more of the aroma and felt a strange tingle coursing in his blood, warm and suffocating. His gaze slowly dropped to become fixed on Dean’s mouth. Castiel licked his own lips in anticipation before quickly moving in and kissing round the corners of it. Castiel was suddenly achingly hard and could think of nothing more that he wanted in that moment than to bend Dean backwards and taste him. 

Dean must have sensed Castiel didn't know what the slick was. He was shuffling gently into different positions while Castiel continued to stare at him, an endearing innocence reflected in his eyes that seemed to call to Castiel through distinctive circles of green. Dean started to run his fingers more carefully over Castiel’s skin. When he moved his hand over his chest, Dean smeared some of the blood from the mark he accidentally scored him with earlier. Castiel gasped at the sudden sting, his breath shaky when he inhaled through his mouth. Castiel caught more of the wonderful chemical drenching his senses when it passed into his lungs and sent a powerful signal of desire straight to his brain. Castiel let out a soft moan of want. Dean carefully pulled his hand away, touching the tips of blood stained fingers to his lips. Dean was now looking Castiel directly in his eyes while he attempted to form shapes with his mouth. He was trying to talk.

“Me.” Dean echoed the word to show Castiel he understood the meaning perfectly. “Mine.” 

Castiel was blinking at him in amazement when he suddenly realized what it was Dean had secreted. It leaked from the gland at the base of the soft dorsal fin folded over the ridge of scales. There was a more delicate patch underneath his groin at the bottom of the second fin. Castiel could see a small hole opening up, stretching slightly every time a fresh burst of pheromone flowed out when Dean got more aroused. Castiel couldn’t break away from watching the tight pull of scales covering Dean's cock where they were starting to move apart from the strain of his erection. Castiel knew enough about animal behaviour to realize Dean wasn’t just trying to show him he was sexually attracted to him - he wanted to mate him.

Castiel finally managed to look away, eyes now moving lustfully over Dean’s body and then back up to his eyes. Castiel dared to massage the protrusion with trembling fingers, the sinful noise it elicited from Dean’s mouth enough to send Castiel over the edge of desire. He eased Dean down until he was lying flat on his back. Castiel angled his own body so he could start to rut against him. The chemical drenched the front of his pants when he moved, the heavy scent continuing to exude from the hole almost overpowering. Castiel circled his hips, pressing his dick against Dean while he fisted the ends of his fingers into the hair at the base of Castiel’s neck. Dean started to push back, just catching Castiel's eyes sliding closed when he gave himself over to the wash of pleasure that almost drove him to the edge again. Castiel knew he was going to come if he carried on, so he reluctantly pulled away and moved his mouth over the pale skin that covered Dean’s stomach. Castiel trailed passionate wet kisses down the line of his tail until his lips were almost touching the delicate expanse of stretched scales. He could feel the warm sensation of softer flesh when he ran his open mouth over it. He could taste the sweet slick.

Castiel knew he wanted it, answering Dean's claim on him with his eyes and his mouth. He wanted it more than anything, but it suddenly felt so wrong. He was supposed to be looking after Dean and teaching him how to be human. Castiel felt like he would be taking advantage of Dean’s desire to just let himself be taken and seal the claim he was staking. Castiel quickly pulled away, forcing himself to sit back and remove his hands from Dean’s body. Dean was looking up at him with disappointment. He thought Castiel was rejecting his advances and refusing his claim. Dean gave him one last lingering look of disapproval and hurt before pulling away altogether and curling his tail around himself. He rolled onto one side and closed his eyes.

“Dean.” Castiel whispered desperately. Dean flicked his tail against him in defiance. The ache in Castiel's chest was now almost as painful as the one still spreading down his dick, but he couldn’t do it. In his own mind, that made him no better than the others. Castiel wanted Dean. He wanted to take him away and stay with him forever, but not like this. He needed Dean to actually say it. Castiel would teach him, help him become the man Castiel knew he could be. He would tell him he would be his mate in words he knew Dean could understand. He refused to let the sexual need destroy the respect and love that had claimed his heart. Castiel needed to believe this was really what Dean wanted. Not because he was lonely and scared, but because he loved him. Castiel would have to wait.

_____


	17. Silence

**Summary for the Chapter:**

> Dean becomes increasingly more confused by Castiel's behaviour towards him, and doesn't seem to know exactly what Castiel wants from him anymore. Castiel is just trying to help keep Dean safe but again he misinterprets his motivation and sadly resigns himself to his fate.

**Silence**

Castiel tried to reach out to Dean again when he murmured his name, but Dean kept curling away from him. He certainly wouldn't need much help in learning how to sulk. It made Castiel smile when Dean edged the tip of his tail towards the warmth of the fire, still refusing to look up. He rubbed at the area where his slick got smeared over the front of his tail when Castiel was lying on top of him. Dean didn’t look at him at all while he cleaned away the last bit before closing his eyes again. Castiel dared to shuffle a bit closer, just managing to touch the end of his fin.

“Dean.” Castiel said again, trying to keep his voice low and use a soft tone Dean might take as an apology. “I want to, I really do.” He added an affectionate sweep of his fingertips along the outer edge. “I wish you could understand me.” Castiel tapped his fingers along the fin, pushing them up a bit higher until he was caressing the lower scales. Dean shuddered slightly at the touch and this time he didn’t recoil. Castiel could smell the lingering provocative hint of musk that affected him so profoundly when it flowed from Dean’s hole. It took all the self-control Castiel had not to lean in again and taste him with his tongue. He tried to get Dean to come closer by tugging lightly at his tail. Dean reluctantly allowed himself to be pulled across the floor until his tail was wrapped around Castiel’s back. The end of it was draped loosely over the rise of one shoulder, but he turned his head to one side to avoid Castiel’s gaze while he stroked him. “Dean, I just want to be sure. I can’t take advantage of you like that.” Castiel continued to try and placate him with the sound of his voice. Dean had no idea what he was saying, but Castiel hoped his tender expression was enough to calm him for now. Castiel almost had a heart attack when Smith suddenly walked in, just as Dean looked like he might be willing to let Castiel touch him again.

“Well?” Smith demanded, before Castiel even had chance to greet him. “What have you been teaching it? Has it made any progress?” Marshall came in closer, and Castiel backed away from Dean as quickly as he could without being too obvious. He didn’t want Smith to know there was a lot more to their relationship than he could ever imagine. Castiel knew he would only find a way to use it against him.

“Not really.” Castiel said quietly. “I haven’t had much time, Marshall. I can’t work miracles. I've started with the basics and he's managed a few simple words, but I'm not sure he fully appreciates what they mean.” Smith was still inspecting Dean where he was resting on his back in front of the fire. His tail had dropped heavily to the floor when Castiel moved away. It definitely hadn't helped to improve his disposition.

“What have you done?” Smith asked slowly, with a hint of accusation. Castiel frowned.

“Nothing.”

“Well, something’s pissed it off. It doesn’t look very happy.”

Castiel looked at Smith in disbelief. He really was completely oblivious to all the suffering he had caused.

“Maybe that has something to do with being taken from his home and locked up like an animal.” Castiel suggested carefully. He was trying hard to restrain the sense of anger he felt at how little Dean seemed to mean to Smith. It was beyond contemptible. Marshall shook his head. It almost looked like he was going to laugh.

“Don’t be stupid, Milton. It doesn’t have feelings.” Marshall sneered at him. Castiel was hoping he wouldn’t comment on how close they were when he decided to make a surprise entrance. Castiel couldn’t imagine how he would be able to explain why Dean had secreted such a substantial amount of pheromone and was very glad he'd just finished cleaning his tail. “Right, I need it to be ready in about an hour. The first sample we had has deteriorated now and we got nothing viable from it, anyway. I’ll send someone up soon to collect it.”

Marshall disappeared before Castiel managed to come up with a response. He felt his stomach sink when he realized what Smith had planned for Dean, and now he knew how he acquired those marks on the front of his tail. Castiel was trying desperately to think of some way of stalling. He thought they might have had more time before Smith wanted to start experimenting on him again. Castiel hadn’t managed to communicate anything to Dean very well recently, and now he was cursing himself for not trying to use the time they had spent together more productively. He couldn't just stand by and watch them abuse him. Dean had wanted to mate Castiel by choice. It was too cruel to take that away from him by force.

Castiel turned to look at Dean again and realized how much he was shaking. His hands were stretched protectively over his groin and Castiel felt so sad for him. He placed one of his hands gently over Dean’s and brought the other one up to touch the side of his face.

“Dean, I'll be with you. I promise I won’t let him hurt you.” Dean might not have been able to understand all the words, but he knew Castiel was trying to help by the tone of his voice and the loving touch on his skin. Dean leaned into the caress and nodded. “Hey… and don’t think I was pushing you away.” Castiel continued. Dean just stared at him, more lines developing on his face when he tilted his head to one side and tried hard to understand. Castiel returned the gesture Dean had offered him earlier, when he covered the mark with his hand. Castiel reached forward and spread his fingers across Dean's chest. “Mine.” Castiel echoed, and Dean blinked when he realized Castiel was answering his claim, not rejecting it. Dean's mouth twitched like he was trying to smile, but there was something about the dull light in his eyes that told Castiel he was still deeply unhappy. 

Castiel made so many promises to Dean before, and they both knew he rarely made good on them. He had a lot of making up to do, but this wasn't the place to do it. Castiel was already starting to think about how he could get Dean away from the institute and keep him somewhere safe. The logistics of it were totally unmanageable. Castiel knew deep down he should really return Dean to the ocean and set him free, but the more time they spent together, the harder it was going to be. Castiel wanted to keep him so badly. Dean had to understand him better before they made any attempt at escape. He would need Dean’s help to make sure they got away safely and that was almost impossible right now.

Castiel had to talk to Shaw again. See if he managed to communicate more with the others before they left for the winter. Time was pressing, and it was the only thing Castiel knew he didn’t have. He was pulled from his thoughts by the sensation of Dean’s hand pressing against the top of his leg. He clearly understood what Castiel meant by that word, and wanted to show him. Dean moved his fingers higher until they brushed up against the line of Castiel's thigh where it dipped underneath him, gasping when he felt Dean touch the edge of his dick. Castiel thought it might have been accidental until he could smell that scent again. He panicked. Castiel knew Smith would be sending for Dean soon, and he couldn’t risk them knowing about his arousal. Smith spent most of his adult life studying animal behaviour and would know instinctively Dean saw Castiel as a potential mate. There would be too many questions and Castiel didn’t think he would be able to answer any of them, so he pulled away again.

Dean looked even more confused than he did before, and Castiel knew why. He sent so many mixed messages over the years, but this one was complicated and it must have been very difficult for Dean to comprehend. Castiel sighed, dropping his head so he wouldn’t have to look at the pain in those beautiful green eyes. Castiel only looked up again when he heard a soft shuffling behind him. His heart broke when he saw Dean struggling to push himself across the floor, dragging his tail awkwardly behind him when he headed back to his tank. Castiel jumped up, offering his hand to help him cross the room more easily, but Dean refused to take it. He managed to jerk his body close to the edge of the tank, spreading one hand across the glass and waiting for Castiel to lift him into the water. Castiel relented. Dean was now completely unresponsive to any attempts Castiel made to try and explain he was just trying to help. He reached one arm around Dean's back before slipping the other one under the bend in his tail. Castiel lifted him carefully, leaning his upper body against his chest so he could move Dean more easily while he tried to get him up to the edge. Dean almost pushed himself into the water as soon as he could, immediately swimming down and settling himself in the bottom corner. As far away from Castiel as he could possibly get. He was blowing streams of bubbles through his mouth while he got accustomed to the change and pulled aimlessly at the edge of his tail fin with rigid fingers. Castiel brushed himself down and wiped some stray drops from his face where they splashed up when Dean’s body hit the water. Castiel walked round to the other side and crouched down so his eyes were level with Dean’s. The thick glass made the image slightly blurry, but even through the dense wall Castiel could see Dean was upset. He put his hand over the glass and felt the cold seep into his fingertips.

“Dean.” Castiel tried. Yet again. “I’m sorry - I’m just trying to help. Dean?” He shook his head sadly when Dean continued to ignore him. “God, I wish you could understand me.” Castiel whispered against the tank, slowly withdrawing his hand. Dean stretched out along the base of his tank and lay on his stomach with both hands over his head. His eyes were still open, deliberately staring at the floor through the glass. Castiel left him to pout for another twenty minutes until there was a sharp rap on the door. He knew it wasn’t Smith. He wasn't polite enough to knock. Castiel reluctantly got up to open it, catching the swift movement of Dean swimming up to the surface from the corner of one eye. Dean was cautiously watching Castiel over the edge of the glass while he opened the door. There were two men in lab coats standing in the doorway. Castiel did a piss poor job of pretending he was calm.

“Ready?” One of the men asked, strangely indifferent to the fact they were about to take biological samples from a mermaid. Castiel looked at Dean over his shoulder. He was expecting him to be frightened, or concerned at least, but now he had no expression at all. Castiel thought it looked too much like resignation, and his heart ached.

“Yes.” Castiel sighed. There was no way he could protest if he wanted to be allowed to stay with Dean. His authority at the institute was now almost non-existent, and he had to be extremely careful if he didn't want to find himself in the same position as Shaw. The two men pushed past Castiel and walked straight over to the tank to lift Dean out of the water. He made no attempt to stop them carrying him out. Dean wouldn’t even look at Castiel while he walked by his side down the corridor. The water was still dripping from his body while they moved through the building. Dean shivered. Castiel knew another sudden change in temperature wasn't good for him, and he was getting cold again. The warmth he usually took from Castiel’s body he couldn’t have right now and Castiel suspected he probably wouldn’t want it anyway. Castiel saw the look on Dean's face when they reached into the tank to pull him out. He had given up.

By the time they got to the laboratory, Castiel felt unbelievably sick. Smith signalled for his assistants to put Dean on one of the tables he was now uncomfortably familiar with. Dean still didn’t seem unusually distressed until Smith turned around. When Dean saw what he was holding, he let out a small panicked gasp and started to shift restlessly from side to side. Castiel went to reach for his hand, but one of the men blocked him.

“Look, it remembers.“ Smith laughed. “Maybe it's more intelligent than I gave it credit for. _Interesting_.” He mused. Dean was trying to push himself up from the table, breath coming in short fast bursts of air while he stared at the machine in Smith’s hands. “I think you might have to strap it down again.” He added, prodding at Dean's groin while he tried to find the opening. Smith pulled his fingers away and inspected some slick that got trapped under the scales when he was aroused by Castiel earlier. Marshall made a small noise of acknowledgement when he realized what it was.

“No.” Castiel said firmly. “I'm not going to let you do that.”

Smith stared at him, entire face contorted with annoyance.

“What the fuck is your problem?” Smith demanded. “You’re a scientist, start acting like one. This was your project to begin with. I'm just carrying out what needs to be done, because you haven't got the balls to do it yourself.”

“This was _not_ what I wanted. This has nothing to do with my project, and you damn well know it.”

“Leave.” Smith said suddenly, gesturing for one of the men to escort Castiel to the door. “I was willing to let you be a part of this, but clearly you're getting too involved with it and I can’t have you getting in the way. You've got some nerve questioning my professionalism after what I saw earlier. You can have it back when I'm finished.” Marshall added quietly, waving the machine at him. Dean was watching Castiel with wide desperate eyes, repeating the word he just learned.

“No leave.” Dean forced out. Castiel was struggling against the grip on his arm while he was pushed to the doorway. “Cas?” Dean begged him.

“I see you taught it how to say your name, how sweet.” Smith concluded with a smile. Castiel couldn’t breathe when he watched the door close behind him. He leaned his back against it, listening to Dean calling out for him.

Dean would never trust him again now. Castiel swore he would stay and not let anybody hurt him.

It was just one more promise he had broken.

_____


	18. Pure

**Summary for the Chapter:**

> Castiel is removed from the examination room, feeling terrible about breaking another promise to Dean. The full extent of what Smith is doing to his captive becomes clear and Castiel is ashamed to admit to himself he wants to be the only one to draw those sounds of pleasure from Dean, and never let anyone else touch him. He may soon get that chance.

**Pure**

Castiel could still hear Dean calling out for him while he waited impatiently outside the door, but he couldn’t do anything right now. He tried the door handle again, even though he knew one of the men had locked it after they shoved him out. Castiel would have to resign himself to waiting in the corridor until Smith was finished. His only consolation was knowing he would probably have a lot more time alone with Dean while Smith was still working on the hybridization project. Castiel was going to use that time to improve the communication between them. So much needed to be said, and Castiel was still really upset Dean thought he didn’t want him like that. He couldn't have been more wrong. Castiel constantly struggled with his emotions and desires every second that passed when Dean was close. The only reason he stopped himself at all was because he wanted to protect him, but Castiel didn’t think he would be able to fight it much longer. He tried hard to stay calm, face pressed up against the door. He could hear the distinctive sounds of clattering metal and waves of muffled conversation. Dean had stopped calling for him, and that made it worse somehow. It meant he didn’t expect him to come back at all. Castiel hoped Dean didn’t really believe he had abandoned him again. Dean must have seen the men forced him to leave. There was some small measure of comfort in the fact this time Dean knew Castiel hadn't left him by choice. It suddenly seemed almost too quiet in the room behind the door and Castiel leaned in even closer. He could hear faint regular gasps. It was Dean. Castiel started to panic when he thought they might be hurting him, and was about to pound on the door again when he realized it was something else. He could just hear the pace of Dean's breaths get faster and louder. Every few seconds there was the familiar thud of his wet tail when it flicked against the table. Castiel knew Dean only turned his tail in circles like that when he was shy or excited. The realization of what was happening caused his stomach to flutter. Now he knew for sure how Smith got his samples.

Castiel wanted to move away, but the sinful noises Dean was making were too much for his imagination and he had to steady himself against the wall. Castiel was trying not to let it distract him. What they were doing to Dean was wrong. Smith shouldn't be allowed to abuse his heat-induced sensitivity like that. Castiel was ashamed at the sudden desire that clawed at his morality when he wished it was him with his hands on Dean. He wanted to be the only one who could pull those sounds from his mouth, but he shook his head and tried to push the thoughts away. Castiel could feel the disloyal twitch between his legs that gave him away. He swallowed hard, biting down on his lip while he listened. There was something about the stilted moans that told Castiel Dean was trying to fight the pleasurable sensations being forced on him again. Castiel barely touched him when they were alone together and he still secreted a substantial amount of slick. 

Even the memory of that scent was too much. Castiel inhaled a shaky gasp, forcing himself away from the doorway before he was overcome by baser instincts at the delicious thought of Dean flicking his tail in wide circles with Castiel’s mouth on him. He jumped back in alarm when he heard a click. The door was suddenly pulled open and the two assistants hurried out. Castiel pushed past them, almost falling into the room in his haste to get to Dean. His view was obscured by Smith’s back, and Castiel could only see the end of Dean’s tail where it was hanging limply over the end of the table. He seemed to be almost completely still save for a small tremble in his lower fin. Smith pulled off his gloves and rolled them into a neat ball before throwing them into one of the waste baskets. When Marshall turned, Castiel could see he was holding a small transparent container with a tube attached. He felt sick again when he realized there was a thick white substance streaking all the way up the inside where Marshall had shaken it to check the cylinder was secure. Castiel knew immediately what it was. He couldn’t bring himself to look. Marshall must have sensed his discomfort and deliberately tormented him with it, waving the object right in front of his face.

“Let’s hope we have more luck with this one.” Smith said, walking over to the sink to wash his hands. That was something Dean should never have taken from him like that. Castiel tried to ignore the undercurrent of sexual abuse, and turned his attention back to Dean. Smith was still moving round the room while he put the instruments into the sterilizer and dropped some paper towels on the tiles to soak up some of the discharge that got secreted from Dean’s hole and dripped on the floor. Castiel just wanted Smith to leave. He was desperate to comfort Dean, needing to be alone with him. Smith nodded over towards the table but didn’t actually look at his specimen. “You can have it back now. You alright to clean up? I can send someone if you want.” He sounded so disinterested now he had what he wanted. Marshall was keen to start work on the fresh sample and Dean’s presence in his laboratory was now just an inconvenience.

“No, it’s fine. I don’t mind.” Castiel said quickly. He didn’t want anyone else in there with them if it could be avoided. He prayed Marshall couldn’t hear how loud his heart was beating inside his chest. “Am I okay to take him back up to the bunkhouse after?” Castiel attempted. The words were forced out. He hated having to submit to Marshall’s self-assumed autocracy but he would do anything to stay with Dean. Smith hesitated, so Castiel tried again, wondering exactly what he must think about his willingness to be alone with Dean. If he suspected something deeper, he never hinted at it. Castiel imagined Smith saw very little of anything in anybody. So many years they had been friends, and Castiel never really knew him at all. “I can start on some new words with him.” 

“Knock yourself out.” Marshall replied dryly, finally moving away. Castiel could see Dean was lying with his head tipped back. His eyes were almost closed, but there was a hint of green flickering underneath his lids. It was fixed on Castiel while he cautiously approached the table. Castiel could see the rapid beat of Dean's heart throb against the exposed skin of his chest. His body was covered with a thin layer of perspiration, cheeks flushed. Some of the longer strands of damp hair at the front had fallen across his forehead. The effects of his recent experience must have been intense. He guessed it was because Dean might be in heat, so every part of him was overly sensitive and very responsive to any touch against his skin.

Dean just lay there while Castiel started to clean him up so they could go back to their little room. He would need to go in the tank first. His skin and scales looked painfully dry, and Castiel imagined he was getting very cold. He wasn't sure Dean would let him touch his body there just yet because he upset him so much earlier, but Dean was in no state to do it himself. Dean looked like he was still coming down from an explosive release, and Castiel was trying not to stare at the small droplets of semen continuing to leak out of him with every pulse of arousal still pumping round his body. His penis must have slipped back behind the ridge in his scales because the secretion was all Castiel could see, ashamed he was almost disappointed. He had often wondered how big it was and what it might look like.

The smaller hole underneath was still covered in the sticky oil containing the chemical that drew Castiel to him with such inexplicable intensity. His nostrils flared without warning when the curls of aromatic air drifted up towards him. Castiel deliberately picked up a large stack of paper towels so his hands were occupied when he moved a little closer. One hand hovered hesitantly over the space while he tried to catch Dean’s gaze. He seemed to be making his own private decision on whether to let Castiel touch him. Dean turned his face towards the wall, body shuddering when he tried to move on to one side. Castiel stopped him, curving his fingers firmly around Dean's shoulder to hold him steady. Castiel started by mopping up the pool of slick spreading over the table and causing Dean to slip around. Smith hadn’t even bothered to put a sheet underneath him this time, so concerned about getting his precious sample he once again neglected Dean’s most basic of needs. Castiel was suddenly very thankful he was working there when Dean got captured, even though that was something he never thought he would be grateful for. It could have been a lot worse. If Dean was going to be caught anyway, at least there was someone there to help him. Castiel didn’t even want to think about how terrible this would have been for Dean if he was alone. In all honesty, he would probably have been dead by now or at least very sick. Castiel let out a deep sigh.

“Dean?” Castiel attempted quietly. He knew Dean was still mad with him, and now he was going to have to confuse him even more by focusing on cleaning him up when all he really wanted to do was kiss every part of him and tempt those same sounds from his lips he heard through the door. Castiel bent his head, pressing his mouth against the skin of Dean’s shoulder where his hand was resting. Dean shifted, and most of his tail slid to the edge and bumped against Castiel’s thigh. He moved his hand lower, curling it around the bend in Dean's tail to try and hold him in position while he dabbed at the scales underneath him. Castiel stroked the towels gently over the lower half of Dean's body until he was almost clean, deliberately leaving the front of his tail until last. He wanted to make sure Dean was comfortable with being touched again, but mostly because he wanted to wait until he was certain Dean finished leaking. Castiel was going to find it hard enough to be that close to his dick and not do anything about it, but if Dean was still aroused it was going to be impossible. “You okay?” Castiel tried once more to get a response, holding Dean's tail down while he managed to ease him onto his back. His scales were now clean and dry, and Castiel left some paper towels underneath him to make him more comfortable. Dean’s eyes were now fully open, staring up at Castiel with a wounded expression.

“Cas lie.” Dean bit down hard on his bottom lip. Castiel never really noticed how sharp his teeth were before. Castiel stroked his thumb across the side of the tail fin and tried to smile. He knew Dean was still hurt and disappointed, but thinking Castiel would deliberately withhold the truth from him was hard to hear.

“I’m sorry, Dean. I didn’t mean to.” Castiel replied, continuing to manipulate the soft ridges of flesh between his fingers. Castiel folded one of the paper towels in half and dared a small sweep of his hand across the warm bulge still evident on the front of Dean's tail. He started to dab tenderly at the sensitive area to remove some of the excess semen and slick. Castiel was moving along the scales as carefully as he could but it was very difficult. It only took a few minutes until the whole area was completely wiped clean, and Castiel smiled to himself when he realized Dean’s tail was moving in wide circles the whole time his hands were on him. He was pretty sure he might be able to persuade Dean to forgive him.

Castiel's main priority now was to teach him, thinking it would be a good idea to get him to understand some words they could use as a code just between themselves. It would allow them to be able to talk even when they weren’t alone. Castiel needed to keep his emotions under better control around the other staff. He would have been able to stay with Dean earlier if he hadn’t started questioning Smith’s methods, and now he blamed himself for not having more self-control. It only made Dean think he had lied to him, and that was almost unbearable. Castiel finished cleaning up in the laboratory while Dean waited patiently for him to take him back up to his tank. He would be able to clean himself properly then. Castiel managed to take care of most of it, but Dean knew the only way to wash it all away completely was to push his body through the water. He also wanted to cleanse away the taint of that man’s hands on him. Not even Castiel realized how much that damaged Dean inside. He had never given himself to anyone. Dean was pure. He had waited all his life to make Castiel his mate and he couldn’t even tell him.

_______


	19. Hope

**Summary for the Chapter:**

> Castiel realizes just how deeply the terrible experiences he has endured are damaging Dean. He knows Dean needs him more than ever and so far he has failed him. Castiel finally admits to himself he is hopelessly in love with Dean and vows to give him some hope that he will eventually be free.

**Hope**

Castiel got rid of the dirty paper towels and sprayed down the counters with disinfectant. His eyes kept darting back to Dean while he moved around, heart aching for him. Dean's tail was just hanging down like he didn’t have enough of anything left in him to care. Castiel thought back to the cold threat Smith made about breaking Dean if they didn’t do what he wanted. Castiel thought Dean looked like he was close to that already, and just wanted to try and bring back that spark to his eyes Castiel fell in love with all those years ago. Castiel swallowed quietly when realization hit him hard, pausing on the last counter top with the spray bottle hanging between his fingers.

He was in love with Dean.

Castiel blinked the admission away. It was too much to even think about with Dean just lying there and waiting for Castiel to save him. The terrible experience had clearly hurt him more deeply than Castiel even dared to guess. Dean was still shivering uncontrollably while he continued to wait quietly for Castiel. His head was bowed low, eyes fixed blankly on the floor. It might have been from the cold, but Castiel suspected it was more likely from the misery of being forced into something so violating. Castiel imagined how destroyed he would feel if their places were exchanged and shuddered at the idea. He knew he was responsible for everything that had happened to Dean, and felt incredibly sick as the word _rape_ surfaced in the front of his mind without warning. He pushed that away as well.

Something suddenly washed over Castiel like a flood. He understood just how much Dean needed him now. He could see it in those haunting green eyes whenever Dean looked at him. He trusted Castiel to protect him and he had failed him, time and again. The crushing feeling of guilt pressed down on him once more. Castiel wasn’t even sure why he held back as long as he had. Denying his touch never actually achieved anything at all, and now Dean looked indescribably sad. Castiel felt a lump rise in his throat while he watched someone so beautiful and strong become consumed by despair and hopelessness. Castiel _was_ the only thing that could give Dean hope and help him out of the dark place he was in. Dean was the only thing that ever gave Castiel’s life meaning.

A warm wave of sympathy surged in Castiel's blood. He hurried over to Dean and bent down at his side, impulsively sliding his hand underneath the weight of his tail. Dean was weak and listless in Castiel’s arms when he struggled to lift him, just leaning into Castiel’s chest as soon as he was upright. One of Dean's hands slipped around Castiel’s shoulders. He dug his fingers into the soft flesh at the base of his neck, desperate for the warmth of human contact. Dean gently tipped his head to breathe in the scent. The intimacy of it wasn't lost on Castiel. He knew that even though he'd disappointed Dean again, he still wanted to be close to him. It made Castiel’s heart feel just a little lighter. He resolved to really concentrate on teaching Dean how to understand the words he needed to hear. Castiel pulled him closer, hitching him up his body so he could carry Dean more easily. Castiel held his breath when Dean rubbed the side of his face into Castiel’s hair while he carried him.

Dean was practically clinging on to Castiel while they moved through the doorway and started to edge down the corridor. Castiel knew it wasn't just because he was afraid of falling. All Castiel could focus on was the need to get him back to the tank. Dean was rubbing distractedly at the scales around his sore opening like he was trying to remove all trace of what happened in the laboratory. Castiel knew he cleaned him thoroughly, but it didn’t seem to be enough for Dean. His trembling subsided slightly by the time they reached the door to the bunkhouse. Castiel guessed Dean thought of that place as his safe zone, and could almost feel the tension melt away when they crossed the threshold. Castiel locked the door behind them and slipped the key in his pocket. He tried to lift Dean into the tank, but he wouldn’t let go. His head was now almost completely buried in the dip of Castiel’s shoulder.

“Dean.” Castiel whispered quietly, attempting to ease him over the edge of the glass. He thought maybe one touch of his body against the water would be enough for Dean to feel the pull of want in his blood and allow him to let the cool relief soak into his skin. If anything, his arms just seemed to hold Castiel a little tighter when he propped Dean’s body up against the glass to stop him from slipping. Castiel cupped his hand and scooped up a small pool of water into his palm, gently running it over Dean’s back and down the curve at the top of his tail while he hushed him with soft whispers of encouragement. Most of the water was soaked up instantly, running through his scales and over his skin. Dean shifted in Castiel’s arms, but he still didn't release his grip which was now almost suffocating. “Dean.” Castiel tried again, his voice muffled when it vibrated across the side of Dean's face. They were so close now, Castiel could feel the spread of the only little pocket of warmth Dean had left. It was pushing out through the centre of his chest and warming the space just over Castiel’s heart. It felt like sunshine and rain at the same time, a confusing combination of concern and desire. Castiel thought he was either going to kiss him or drop him, whichever sensation managed to surface first. “You need to get in the water.” He added, trying to keep his voice soft and persuasive. He could sense how fragile Dean was right now. Castiel lowered him slowly just beneath the surface, subtle lap of water undulating over the lower section of his tail fin and across the base of his back. Dean made a small noise when Castiel leaned over the side of the glass. He was dangerously close to toppling in if Dean continued to hold him so tightly. Castiel let out a startled gasp when his feet slipped on a puddle that formed where some splashed over the side. “Come on, you’re cold.” Castiel soothed. Dean finally relented and released him, dropping heavily into the tank. A swell of displaced water was thrown out and down Castiel’s front, leaving his shirt completely soaked. Dean swam in small circles, desperate to wash away the hateful memory by spinning and twisting as quickly as he could with whatever energy he had left. His long fingers clawed at the spaces between each damaged scale in turn, but he seemed to be much more relaxed while he bathed in the familiar comfort of his surroundings. Dean sank gracefully to the bottom.

Castiel tried to brush the water from his shirt, but it was pointless. He was absolutely drenched and the only option was to change before the cold started to chill his skin. He set to unbuttoning his shirt and slipped it from his shoulders. Castiel reached for a towel and started to rub at the front of his chest and down his stomach. He suddenly paused when he realized Dean was staring at him with so much intensity, Castiel couldn’t pull away. The green eyes were fixed on the contours of Castiel’s chest, both of Dean's hands splayed flat across the thick glass that separated them. Castiel stared back, towel slipping through his fingers. They watched each other for a few seconds before Castiel finally managed to tear his gaze away. He coughed and bent down to pick it up, trying to hide his body. He didn't know why but he suddenly felt very vulnerable. Dean slowly moved away to cleanse his fins and scales. He would occasionally glance over to Castiel while he slid effortlessly through the water - just to make sure he was still watching.

Castiel walked through to the bedroom and grabbed one of the t-shirts he left in the apartment last time he stayed there. It had the symbol of the institute emblazoned over one corner and the letters MBRI Maine stitched underneath. Castiel felt his heart sink when he saw it. He was so ashamed he had ever been associated with that place. When he came back, Dean was hanging over the wall with his arms resting limply down the outside of the glass. Castiel smiled at him. Dean seemed slightly less distressed than he did earlier, but he still looked sad. Castiel quickly climbed the bottom steps so their eyes were level.

“Do you want to sleep?” Castiel asked slowly. Dean frowned at him, tilting his head. “Sleep, Dean.” Castiel pressed both palms together and rested his head on his hands. He closed his eyes in the hope Dean would understand, but when he opened them again Dean was still frowning. Castiel realized it was a stupid question. Dean would be unlikely to understand. His head wasn't used to resting on a soft pillow, or in the shelter of a warm embrace. Castiel tried again. “Sleep, bed.” He pronounced the words carefully so as not to lose their meaning, tipping his head towards the bedroom to illustrate the point. Dean put his arms up and nodded enthusiastically.

“Bed. Cas.”

Castiel could feel the warm flood of many implications of that idea spread in two different directions at the same time.

“I meant to sleep. I thought you might want to rest.” Castiel added quickly. He could feel his face flush pink when his dick jerked forward. It was a pleasant distraction, but there was still something dark and terrible left unsaid, so he swallowed the feeling down. Castiel lifted Dean out of the water to hold him close again, wrapping Dean in another clean towel before carrying him through to the bedroom. The temptation of fresh cotton was too much to even think about right now, so Castiel placed a pile of pillows in the chair by the side of the bed and eased Dean back into it. Castiel tried several times to get Dean to sit upright, but it was hopeless. He kept sliding down and knocking the pillows on to the floor. Castiel could see Dean was getting more and more frustrated with every fruitless attempt, until there was clearly no alternative but to lay him down. The minute he moved Dean to the bed, Castiel knew he was lost.

Dean was suddenly reaching up for him, watching the movement of Castiel's hands when he nervously bit into one fingernail. Dean was still so desperate for the contact, Castiel couldn’t refuse him so he sat next to Dean on the edge of the bed. As far away from him as was physically possible on such a small space. Castiel couldn't shake the memory of the look that crossed Dean’s face when he was cleaning himself in the tank. The way he tended to each scale around his opening so attentively made Castiel wonder just how much Dean had needed to erase that experience from his body. He felt horrible again.

Castiel managed to get Dean wedged between a mass of angled pillows and dared to bring one leg up onto the bed, careful not to startle him. He decided to try and give them both something else to focus on while they were so close, and alone.

“Okay, Dean.” Castiel tried to pull himself free of all the wicked thoughts he was damping down at the back of his mind. He tried to get Dean's full attention by waving one hand in front of his face and leaning in a bit closer. “I want to start on some new words. Do you understand?” Castiel asked, eyes widening while he waited for a response. Dean continued to watch him patiently. Castiel loved the way the lurid green of his eyes seemed to flicker while he studied the movement of Castiel's mouth when he spoke his name. Dean didn’t answer, but Castiel was fairly certain he knew what he meant. They started this way before, with Castiel trying to show Dean how he managed to form different words depending on the shape of his mouth, or the click of his tongue. Castiel tried not to concentrate on that too much, and reached for one of Dean’s hands. He lifted Dean's fingertips up to his lips to show him how to model the sound. Castiel knew he had to focus hard on the lesson, and not the gentle brush against his mouth. He almost forgot himself again for a moment. Nothing much had changed between them over the years. Dean was a little more damaged and Castiel had developed a deep sense of guilt, but other than that they were almost the same.

Sometimes it felt like they were still two lost little boys just trying to find each other.

Castiel intended to start with the basics again at first. Dean always struggled with the softer sounds and syllables. They were strange and unfamiliar to him, but he tried for Castiel anyway. They practiced names again, and then words for some of the random objects just lying round the bunkhouse until Dean started to look tired. Castiel decided to try just one more before he let Dean sleep. Something he was thinking about a lot since they returned to the room. It was the one thing he wanted so desperately to give back to Dean.

 _Hope_.

_____


	20. Powerless

**Summary for the Chapter:**

> Castiel receives an unexpected phone call that forces him to accept he needs to let Dean go to keep him safe. The time seems to have come for them to part, but Castiel realizes he really doesn't want Dean to leave. He makes an impulsive decision he has held back far too long already and finally gives in to his desire for Dean.

**Powerless**

Castiel was awoken by the insistent tone of his cell as it vibrated against the inside of his pocket. He stretched lazily and turned over onto his back. He slowly opened his eyes and realized he had fallen asleep next to Dean again. Dean was curled into his side like he was trying to steal all the warmth he could from Castiel's body while they lay together. Castiel could feel the tight grip of an arm around his waist, and turned his face to look. Dean's eyes were closed, so peaceful just making small snuffling noises in his sleep when Castiel shifted his body to get more comfortable. Dean just pulled him closer, digging sharp nails into the skin where his hand had slipped underneath Castiel's shirt. Castiel watched him silently for a few seconds before he thrust his fingers into his pocket and pulled out his phone. He blinked sleepily when he flicked it open, sitting up quickly when he saw the caller ID flashing brightly on the screen. Dean’s arm was now resting on his thighs.

“Shaw?” Castiel gasped in surprise. He kept his voice low so as not to wake Dean, pushing his body a bit further up the bed until his back was resting against the wall. “Hey, how are you?”

“I’m okay.” Shaw replied, after a brief pause. “Sorry, did I interrupt something?” He asked cautiously. Castiel looked down at Dean again. A flush of heat sprang to both cheeks.

“No, not at all.”

Castiel could almost hear the other man hum his uncertainty through the phone.

“I thought you should know, they’re going to help - the mermaids.” Shaw clarified, in response to Castiel’s stunned silence. “They’re going to help your friend get away. We’ve come up with a plan of sorts. Probably risky and timing is crucial, but it might just work.” Castiel couldn’t find anything to say. His stomach suddenly felt tight, a wave of nausea assaulting his senses with the thought of having to let Dean go. “Castiel? You there?” Shaw prompted.

“Yes. Sorry, I’m here.” Castiel said quietly, fear gripping his throat. He wasn’t ready to say goodbye.

“Isn’t that what you wanted?” Shaw asked. Castiel could hear the confusion in his voice. “Can you meet me tomorrow to talk it over? I know they won’t let me in if I come up to the institute. Reckon you could get away for an hour or so? Will he be alright?” There were too many questions at once, and Castiel couldn’t think straight while he processed all the implications of helping to finally set Dean free. He shamefully bit into his lip, closing his eyes after studying the beautiful contours of the man that was still draped all over him.

“I’m not sure. Honestly, I’m scared to leave him for too long.” Castiel answered. He could feel his heart pound as the lie passed his lips, cursing himself in his head for allowing Dean to have so much control over his emotions without even trying.

“Oh, okay.” Shaw sounded disappointed. He spent the best part of a week trying to communicate with the two mermaids who visited the cove, and his main aim had always been to help Dean return to the ocean. He wasn’t really sure how to respond. “Castiel?” Achak asked slowly. “You _do_ want to help him escape, don’t you?”

“Of course.” Castiel stammered at last. “Yes, of course.” He managed to subdue the selfish desire to keep him so close just a little longer. Castiel forced himself to think about what was actually best for Dean. He needed to be back in the water. There was no other choice to make. Castiel sighed, tightness spreading quickly from his stomach to his throat. “I’ll see what I can do.” He added at last. “I can probably manage to get away for a bit. I’ll tell Marshall I need to pick up something for Dean.”

“Dean. Yes, of course... alright, then.” Shaw replied, wondering if Castiel’s sudden reluctance to release the creature had anything to do with the attachment he had clearly developed for him. Shaw suspected the connection between them was far from one-sided, and it filled him with concern. “I’ll wait on the beach for you. If you can get away, meet me at midday. I’ll be waiting.” Castiel heard a click. He was still sitting motionless on the bed with his phone resting in one hand when he felt Dean stir next to him. Castiel looked down again just as the green eyes fluttered open. He reached down, gently stroking Dean's hair when he wrapped his tail over Castiel’s legs and rubbed his face against his side.

“Hey.” Castiel breathed, wriggling back down next to Dean and leaning his body towards him so their eyes were level again. Dean ran the edge of his lower fin along the side of Castiel’s thigh. Castiel knew he should tell Dean they had a plan to help him, to give him hope. He wondered if Dean would even want to leave him again. He still wasn’t sure if Dean had returned that last summer to find him. Maybe he would never know. “Dean, there may be a way to get you out of here.” Castiel whispered, through the pain that clenched around his heart. Dean frowned at him again, waiting for Castiel to explain in words he could understand. Castiel sighed, searching for another way of sharing what was said during his conversation with Shaw. He pointed outside and shaped one hand in a gentle undulating motion like he was trying to model the movement of a wave. “Big water. Home.” He added, forcing a smile. Dean was still staring at him with wide eyes. He pushed himself up on the arm that wasn't holding on to Castiel, not sure he would get the response he wanted to his next question.

“Home. Cas come?”

Castiel felt everything sink into his stomach.

“No, Dean.” Castiel shook his head sadly. He couldn’t look into those eyes. “I can’t come.” Dean stroked the tips of his fingers gently over Castiel’s chest, pushing his tail back so he could slide closer to him.

“Cas. Come.” Dean said again, and this time Castiel realized it wasn’t a question. Castiel turned his face away and reluctantly slipped free of Dean’s embrace. He sat up on one side of the bed and let his head fall into his hands. He could feel Dean reaching for him, tugging hard at the back of his shirt. “Cas?” The stilted way Dean always pronounced his name never failed to make Castiel smile, but he felt so torn he couldn't even look at him. He knew he would cave.

“No, Dean.” Castiel whispered, tearfully pushing down all the doubt and forcing his determination to the surface. “You need to go. I need to let you go.” He muttered to himself, moving away from the bed. Castiel knew if they lay together much longer, his already faltering resolve would crumble. He had always been powerless to stop himself from falling in love with Dean, and now the time had come for them to finally part it hurt more than he ever thought it could. He inhaled a deep breath and left Dean alone in bed. Dean heard the door click shut as Castiel went in search of Smith.

_____

Castiel lied almost effortlessly when he tried to get Marshall to agree to let him have an hour off the next day to pick up some essentials. Smith wanted to know why _his pet_ needed anything they couldn’t manage to provide at the institute.

“He’s not my pet.” Castiel said defensively, staring out the window and across the ocean. Smith sighed melodramatically and ignored the comment.

“I’ll think about it.” He answered, with deliberate indifference. Smith knew exactly how to get a reaction from Castiel. He saw how agitated he got at the mere mention of Dean, so he just did it all the more.

“Fine.” Castiel spat out. He couldn’t even look at Smith anymore. The deep contempt he now felt for him was almost stifling when he was in his presence, and Castiel didn’t want it to show on his face in case he tried to use it against him. He could still carry out the threat he held over him.

“Tell you what.” Smith started slowly. “If you can manage to get it to talk to me, I’ll let you go - one hour.” He smiled to himself when he saw Castiel’s shoulders tense. It almost felt like he was now the one being held captive by Marshall’s demands. “I'll come up to the bunkhouse this evening after supper to check in and see how much progress you have actually made, inbetween whatever else you two have found to do to pass the time.” Castiel thought there was an underlying hint of suggestive sarcasm in the way he spoke the last sentence, but he didn’t dare to question it. Castiel was glad he had his back to Smith when he reached for the door. Marshall couldn’t see the flush spreading rapidly across the base of his neck when Castiel thought about all the things he'd like to do to Dean in those long hours they spent alone together.

When Castiel returned, Dean looked like he had almost drifted off to sleep again. His body was stretched out across the entire width of the small bed, tail drooping over the edge. Castiel helped him sit up and gave him the bottle of water he grabbed from the fridge on the way back to the bedroom. Dean took a long sip before pouring the rest over his lower fin and the scales that joined his tail to his body. The water was absorbed quickly when it ran down him.

“Right.” Castiel said decisively. “We need to impress that asshole later, so sit up properly and start practicing.” His voice was light and teasing when he gently eased Dean’s tail over the sheets so he could sit down next to him again. Castiel went over the words Dean learned earlier, trying to get him to say Smith’s name to show Dean how best to greet him when he came by later. Castiel reiterated _hello_ and _Mr. Smith_ a few more times, until he was fairly certain Dean would be able to repeat it later. Castiel was ambitiously working on trying to get Dean to form a sentence, but he kept struggling with the softer syllables. Castiel gently took hold of his face and tried to manipulate Dean's voice so he sounded more human. He touched Dean's mouth while he repeated the words again and tried to coax him into copying it. Castiel was staring at Dean’s lips when they suddenly closed around his finger. Dean sucked the whole length inside his mouth. Castiel was transfixed, holding his breath when he felt the top of Dean’s rough tongue caress the sensitive skin of his fingertip.

“Dean, please don’t do that.” Castiel managed to gasp out. His eyes never left Dean’s face while he watched his finger disappear in and out of that soft wet space. “I’m supposed to be teaching you. You’re making it exceptionally difficult to concentrate, and we’ll both be for it if Marshall isn’t impressed later.” Castiel murmured. The meaning was completely lost on Dean. Castiel knew he couldn’t possibly understand a string of so many new words at once, and he only really said it to remind himself what he was actually supposed to be doing. “Dean, words.” Castiel insisted, reluctantly pulling his finger away. Dean pouted at the loss. Castiel smiled at the look of indignation on Dean's face and shook his head with frustration. “Believe me, I would much rather be kissing you right now.” Castiel tried another smile, but his expression quickly faded as soon as Dean recognized the word _kiss_. Dean leaned in towards him, parting his lips and waiting for Castiel to touch him. “Dean.” Castiel whispered, his chest heaving with fractured breaths while he resisted the desire to give Dean what he wanted. Castiel stared at his open mouth, consciously fighting the wave of lust that suddenly washed over him. He was powerless to finally let his body give in to the desperate need to feel Dean’s tongue gliding over his own. Castiel hesitated for one last second before all his resolve shattered. He grabbed Dean’s face in both hands and pushed their mouths together in a frantic kiss that took his breath away. Dean responded at once, clawing at Castiel’s shoulders to pull him down. Dean wound his tail around Castiel's ass to hold him fixed above him. Castiel could feel the thick slick shoot out the front of Dean's opening and spread across the material of his pants where he covered Dean’s body with his own. Castiel fumbled with his zipper while Dean poured seductive moans into his mouth. Castiel was fully hard within a few seconds. He had waited so long for him.

Castiel slipped out his pants while their mouths stayed fixed together, rolling around on the crumpled sheets. Castiel could feel the press of Dean’s erection rubbing against his own when he thrust his hips down, drawing more hums of pleasure from those moist lips. He gasped when Dean curved his tail more tightly around him and flipped Castiel on to his back. Castiel was watching Dean trace hot kisses all the way down his chest and over the lower stretch of his stomach just above the band of his shorts. Dean continued to drag his tongue over Castiel’s skin before sliding down the bed so he could mouth around the line of Castiel’s dick through his boxers. Castiel groaned, pushing his fingers through Dean’s hair and instinctively guiding him lower. Dean took the shorts in his teeth and pulled them over Castiel’s cock so it was exposed and rigid, resting heavy on his stomach. Dean licked at the tip, flicking his tail in wide circles when he tasted Castiel for the first time. Castiel could feel the rough surface of Dean’s fingertips stroking up and down his length while the rush built inside him, and knew he couldn’t last. Many years of repressed desire and illicit thoughts crashed together when he felt Dean sink his lips down until it was completely covered by his mouth. Castiel was ashamed how quickly he came. He watched Dean take it all when he spilled into him, curling his fingers more tightly into his hair. He let out a low moan of ecstasy while Dean continued to suckle at his dick until there was nothing left to swallow.

Castiel pulled Dean up, wrapping his arms around his back while the beautiful feeling slowly faded away. He lay back on the pillow and placed one arm across his eyes. Castiel steadied his breaths, shivering until the pulsing finally stopped. Dean had leaked all over the sheets and Castiel could smell the delicious scent of his release as it permeated the small room. The air smelled of sex and pheromones and the sea.

They held each other close as more precious time slipped away. Castiel suddenly jumped up when a spike of fear thumped against his spine. How could they possibly have fallen asleep again? He realized it was dark outside, and picked up his phone to squint at the numbers in the dim light. They only had minutes before Smith would be coming up the corridor.

_____

 


	21. Dishonesty

**Summary for the Chapter:**

> Castiel receives an unwanted visitor when Dean attempts to show Smith the progress he has made in learning how to communicate with his captor. Smith appears to be placated until he realizes there is an all too familiar scent in the room that suggests Castiel and Dean have definitely not spent their time studying.

**Dishonesty**

“Shit.” Castiel murmured, throwing back the sheets and pushing himself out of bed. His blue eyes were frantic while he searched for his discarded jeans in the darkness. Dean stirred, a sudden rush of cold air vibrating against Castiel when he got up. He started to realize how little time they had before Smith was due to arrive. Castiel called Dean’s name while he pulled on his pants, his pleas for Dean to wake up becoming more insistent while precious seconds ticked by. Castiel knew he would have to carry Dean back through to the tank as soon as he could. The terrifying concept of having to explain why Dean was in his bed again was too distressing to even contemplate. He was lucky they were allowed to spend so much time together already and had no desire to risk that privilege being taken away. Castiel could still feel the throb of desire deep in his stomach and the experience with Dean a couple of hours earlier was still fresh in his mind, and very distracting. Castiel had waited a long time to feel Dean’s mouth on him, vowing to return the favour as soon as they were alone again if Dean would let him. The treacherous memory of sexual abuse kept surfacing on the edge of his thoughts, and made him feel almost constantly sick. Castiel shook off the feeling of resentment that still burned in him. He wanted to be the only one to touch Dean like that.

Dean already staked his claim on Castiel as his true mate, his dick starting to pulse again at the thought. He pushed the swelling down and tried to force the feeling away. Every time he was around Dean lately, Castiel couldn’t help but become aroused. The heady scent of Dean’s release that still stained his jeans was drifting upwards and making him unsteady every time he inhaled. There was something about the way it pulled at his senses, like nothing else mattered. Castiel flicked on the small lamp so the light wasn’t too bright for Dean, and gasped when he realized the sheets were covered in slick. It looked darker than usual. He suddenly remembered what Shaw said. Dean’s mating cycle only lasted a few weeks and then he would feel the need to return to his pod and leave for the open ocean. It meant their time was running out. Castiel felt so guilty when he understood Dean only ever came in so close to shore just to be with _him_. To show Castiel he wanted to be with him. To mate him.

It really was all his fault, however unintentional it may have been. Castiel tried to straighten out the sheet where it was rucked up around Dean’s tail. Dean stretched sleepily on the bed and lifted his fin slightly at one end. It rippled with the familiar sensation of contentment when he remembered he was in Castiel’s bed again. Dean flexed his fingers while he pulled out the tension in his muscles, and Castiel saw the sharp points of his delicate claws catch the light. He imagined how much damage Dean could really do to him, or to Smith - or in fact to anyone who had participated in his capture and shameful confinement in the small tank he had been forced to call home. Castiel felt another wash of protective sympathy flood through him as he watched Dean’s sleek body curve and twist while his senses returned. Castiel felt his stomach tremble when he imagined Dean’s smooth scales rubbing against him, pressing him down and covering his body with his own until he could feel his heartbeat next to his skin.

“Dean.” Castiel tried again. “Come on, wake up.” He quickly fastened his jeans and patted down the drying fluid that had seeped into the material and left a shimmering residue on the surface. He tried to brush it off, noticing it didn’t seem to have lost any of its potency when he caught another breath of balmy air. Castiel almost groaned at the feeling it elicited in him. “Dean.” A small flick of his tail and a deliberately seductive flutter of those long eyelashes were all Castiel focused on when Dean pushed himself up on his elbows and stared back in the dim light. Castiel was powerless to resist, effortlessly drawn back to the bed by his eyes alone. Castiel swept one hand gently through Dean's damp hair, leaning in towards him again. Dean was so inexplicably distracting it scared Castiel sometimes at how defenseless he really was against him. He sighed, forcing himself to stand before he got caught in another kiss that would undoubtedly be their undoing. If Smith caught them making out, Castiel would probably never see Dean again, and his heart couldn’t take it. At the least, Smith would somehow find a way to use Dean against him and make him watch Marshall torture him. He couldn’t take that either. Castiel had no doubt Smith would be more than willing to carry out his threat if he even suspected there was something more between them other than ward and guardian.

Moving away from Dean where he lay stretched out naked on the bed took every shred of conscious effort Castiel still managed to possess. It started to overpower him completely since his fateful conversation with Shaw. A shameless and dishonest thought suddenly gripped him when he remembered snatches of the hurried conversation they shared earlier. Castiel’s guilt ran deep when he considered the conditions of the arrangement he made with Smith. He looked down at Dean’s face, flushed from the warmth of sleep and he stalled.

_God, how he wanted to keep him._

Castiel thought Dean looked anxious, but he couldn’t tell him what was going through his mind. If Dean didn’t talk to Smith, then he probably wouldn't let him go to meet Shaw at the beach the next day and they wouldn’t be able to discuss a way to get Dean home. Castiel hated himself for even considering it at all, but that little spiral of deceit was already winding its way up his spine. He was just about to tell Dean not to speak to Smith, when his thoughts were disturbed and scattered by a pounding on the door in the other room. Marshall had tried to open it, but Castiel made sure to lock it after they came in. He could hear his name being called in a demanding and frustrated tone that did little to soften his desire not to communicate with Marshall at all.  

“Hang on!” Castiel called back, quickly reaching for Dean. He managed to lift him, but Dean was still sleepy and felt much heavier than usual. Holding him up was difficult, but Castiel knew if he didn’t get him back to the tank it would look highly suspicious, and he was in no mood to placate anyone or answer demanding questions. Dean seemed to understand why Castiel was so eager to get him back into the water and just leaned into him, wrapping his arms tightly around his neck. He pushed himself up to rest the top of his body against Castiel’s chest to try and make it a little easier for him. Castiel was still whispering mumbled apologies in his ear when he tipped him over the side of the glass. It was desperate and hurried, and Dean hit the surface with a loud splash. A stream of water surged over the side. Castiel could hear Smith fumbling at the loop of many keys he carried around the institute. Castiel decided long ago the experiment was probably just a cover for some personal and twisted agenda. The whole thing now appeared to be some kind of misdirected power trip that Smith seemed to be enjoying rather too well.

“What the hell is going on in there?” Came a muted call from the other side of the door, soon followed by the pounding of a fist and a curse.

“Just a minute!” Castiel shouted back, irritated by yet another intrusion on his alone time with Dean. Castiel knew he had to keep their relationship a secret, and it was becoming increasingly difficult as the days went by. He was sure Smith already suspected something. He dropped comments to Castiel and some of the others who worked in the laboratories downstairs. Castiel was becoming used to the accusatory looks on his rare visits to other parts of the building. Few people bothered to even talk to him anymore, and when they did he could see the cold pity in their eyes and the way some of them shook their heads when he passed them by. He didn’t care.

Dean was worth it.

Castiel managed to get Dean safely back to the tank with just enough time to rush through to the bedroom and strip off the ruined sheets. He was stuffing them into a cupboard when he heard the lock click in the other room. Castiel knew he was still flushed, and now he felt far too warm and out of breath from the exertion of covering up the evidence of their sexual encounter. He greeted Smith with a fake smile when he watched him approach the tank. Smith stared at Dean through the glass for a second before ignoring him completely and looking at Castiel. Marshall tapped his finger against his temple. Castiel felt his heart sink into the pit of his stomach while he waited for Smith to explain what the hell that was supposed to mean.

“How long has it been back in the tank?” Marshall asked uncertainly. His gaze kept flitting back to Dean, a look of doubt starting to develop on his face. “Why did you lock the door?” He continued, without waiting for Castiel to answer the first question, like it didn’t really require a response. Smith was looking between them with something dark behind his eyes. It passed after a few seconds when he obviously decided against voicing his concern for now. For the second time in as many minutes, Castiel became painfully aware they were running out of time. He always thought he had been very secretive and managed to hide his feelings for Dean well when they weren’t alone, but he could see the expression in Smith’s eyes. He knew right then Marshall suspected a lot more than Castiel gave him credit for. He issued a low hum but nothing more. Castiel felt himself relax, lines on his face slowly fading away.

“I didn’t want anyone to disturb us. He was practicing very hard this afternoon.” Castiel answered, smiling inside at the warm memory of Dean sucking him deep into his mouth. “So you'd be pleased with his progress.” He added quickly, dipping back into the shadows of the doorway to hide the spread of pink that was budding on his cheeks. Castiel didn't like the way Smith was looking at him, nervous anticipation rising when he drew closer. Dean propped himself up on the edge of the glass, silently watching the exchange. He hadn't fully understood exactly what they said, but he could tell from Castiel’s expression he was scared. The two men were staring at each other as the tension grew, and Dean thought it would be a good time to try and distract the man from focusing too much on Castiel. Dean pressed his tongue behind his teeth so he wouldn’t lapse into the familiar clicks he was used to making, and opened his lips to form a small circle.

“Hello, Mr Smith.” Dean managed to push out brokenly through the uncomfortable shape he forced his mouth to take.

Marshall looked genuinely surprised, turning his attention straight back to the tank and peering at Dean while he waited for him to say something else. Castiel could feel the panic rising inside his chest, frantically shaking his head behind Marshall. He didn’t want Dean to say anything. That would mean he might have to go back, and Castiel didn’t think he could take losing him again. He wanted more of that sweet drench of pleasure he felt when they lay in bed together. He cursed himself for even thinking it.

“Huh.” Smith muttered, crossing his arms over his chest. He was waiting for Dean to speak again. “Good, show me something else.” He demanded, fixing his eyes on the movement of Dean’s mouth while he prepared to say the words Castiel taught him earlier. Dean wanted to help. He wanted to give Smith whatever he asked for so he could stay with Castiel.

“Cas.” Dean said proudly. He pointed at Castiel before daring a shy smile, moving his hand back towards his body and covering the space over his heart. Smith stared at Castiel with a dark look burning behind his eyes. Castiel swallowed hard when Smith walked back over to him and inhaled a deep breath. Castiel could see his nostrils twitching when he got near the bedroom door.

“He learns fast.” Castiel said, as quietly as he could over the sound of his own heart pounding relentlessly behind his ribs.

“That right?” Smith bit out, eyes narrow enough for Castiel to understand he didn’t believe they had actually spent much time practicing words at all. He tried to stand firm when Smith got close enough for Castiel to see the glint of teeth behind the curl of his lip. “You think I can’t smell that?” Marshall said suddenly, leaning into Castiel’s space. He drew in dangerously close, and Castiel could feel a stream of exhaled breath skim across the side of his face.

“What?” Castiel gasped slowly, desperate not to give away the fear that gripped him when he realized Smith was referring to the scent of pheromone that still hung heavily in the air.

“Castiel.” Marshall said patronizingly. “I have spent most of my life studying animals and their behaviour. I know what _that_ is.” Smith added quietly. He looked more disgusted than anything else, but Castiel still didn’t give him a response. “Move aside.” Smith demanded. Castiel glanced fearfully at Dean before sighing in defeat and turning his body away so Marshall could get past him. He pushed the door open the rest of the way and sniffed at the air. “I want you to tell me why that _thing_ has been leaking slick while you two have been locked up alone in here.” Castiel was desperately trying to think of a believable excuse, but nothing would come out as the man continued to glare at him. "Don’t even try to lie to me. I want to know right now exactly what is going on here. Tell me the truth, or I'll make sure you never see each other again.”

_____


	22. Resignation

**Summary for the Chapter:**

> Castiel manages to persuade Smith he can be trusted completely by lying about his motivations for keeping Dean close. Castiel soon realizes Dean's unnatural environment is making him sick and decides he must now stop at nothing to get him home.

**Resignation __**

Castiel was just staring back in alarm when a disgraceful idea suddenly came to him. With Smith demanding an immediate response, it was the only thing he believed might save them from his wrath. The words left his lips before he could even think about what he was saying.

“Well, I wanted to see if what you said was true so I abused him, like you.” Castiel didn’t really think he sounded all that convincing, waiting nervously to see if that managed to get a reaction. Smith suddenly laughed.

“Really?” Marshall said, through a twisted smile. “Interesting. I didn’t think you had it in you, Castiel.” He seemed disgustingly proud of the fact he had managed to get Castiel to understand they could mistreat Dean so badly and get away with it. Castiel bit his lip in shame while he watched Marshall saunter back over to the tank to rest one hand on the glass. Dean seemed to be listening to their conversation, muted by the density of the water. Castiel was almost certain Dean wouldn't have understood what he said, but Castiel hated betraying him like that. It didn’t matter that it was a lie. If it meant they could stay together for a little while longer, then it was something that just had to be done. It would probably only serve in buying them some time, but it would hopefully be enough for him to get Dean free, once and for all. Castiel knew he had no choice but to get him back to the sea now. The fateful admission he just shared with the contemptible Smith would have serious implications for Dean’s future. His eyes locked on the green gaze now fixed on him from the prison of his tank.

“Yes. Well, I realized it was pointless trying to fight you on this anymore.” Castiel continued, swallowing down the burning hatred he felt for himself. He turned his face away so he couldn’t see the imperishable trust reflected in Dean’s eyes. “By the way.” Castiel tried hesitantly. “You said I could maybe venture out for a bit tomorrow? I thought I might pick up some things for him.”

“Like what?” Smith scoffed. “We have enough food for it downstairs. What else could it possibly need?” The cold intonation in his voice made Castiel shiver.

“I know, Marshall. I was just thinking he might get sick if we don’t start providing him with a more varied diet.” Castiel blinked at his own pathetic attempt at persuasion. It sounded ridiculous, but he thought Smith might just buy it. Castiel held his breath in hopeful anticipation. He knew Marshall probably didn’t trust him at all after his many attempts to protect Dean. He had made such a mess of everything. Smith looked like he was going to refuse the request at first, but then he tapped his fingers against the glass like he was contemplating a response.

“Okay.” Smith agreed, after a painful pause. Castiel felt his shoulders relax, hoping it wasn’t too obvious. “I’ll give you the hour you asked for. I'm marginally impressed by the fact you managed to get it to learn my name, and if you are now on _my_ team, so to speak, then it would seem reasonable of me to return the favour.” Castiel nodded, muttering his thanks. “However.” Castiel felt his stomach sink. “It's partly a test to see if I can really trust you now. I know you are fond of it… please don’t bother to deny it.” He added, lifting up one hand to silence him. “It likes you. I can tell, and you do seem to have built up some kind of mutual understanding with it and that is good for _me_.” Smith mused thoughtfully. Castiel had no doubt that man had something dark and terrible planned, and was going to use Castiel's affection for Dean for his own purposes. He would make sure Dean was free before that ever happened.

“I would like to think my hours spent trying to educate him have not been wasted.” Castiel answered, deliberately hiding the sarcasm in his voice when he feigned a smile.

“Indeed.” Smith wasn’t really listening anymore. Castiel was glad of it. He just wanted Marshall to leave, so he could try and explain to Dean their time together would soon be over. He didn’t want to lose him, but he had to try and make amends for all the damage done. Maybe Dean would come back in another ten years…

Castiel thought he was going to throw up.

“Right, I need to get back down to the lab to finalize arrangements for tomorrow.” Smith commented, running one hand along the side of the tank. He seemed strangely entertained by the way Dean’s eyes followed the movement with interest. Smith hummed his approval. “It amuses me.” He murmured, letting out a cruel laugh when he pulled his arm away. “Incidentally, you may be interested to know we have had a small measure of success with my hybridization project. Nothing conclusive you understand, but… well, I'll show you tomorrow if you can manage to restrain yourself from interfering again. _Can_ you behave now, Milton?” Marshall raised one eyebrow, waiting for an answer. Castiel had tried very hard to forget about that. The idea of finalizing any arrangements that had anything to do with Dean still filled him with concern.

“I’m sure I can.” Castiel lied. He wasn't going to give anyone the opportunity to molest Dean again, but that was something he decided to keep to himself.

“Very well. In that case, you may accompany it to the lab tomorrow for the procedure. Don’t be late back from your little shopping trip or I may have to start without you.” He tapped the glass on his way to the door, signalling for Dean to come to him by curving his finger and wiggling it towards himself.

“What procedure?” Castiel asked in a whisper, gaze hesitantly drifting back to Dean. He didn’t like the sound of that at all.

“Come on… come here.” Smith tried to coax Dean to the edge of the water and ignored Castiel completely. Dean looked up for approval, so Castiel reluctantly nodded. Dean pushed himself upwards with a small flick of his muscular tail and gripped the side nearest Smith. Castiel silently admired how elegantly Dean moved through the water. He could have watched him for hours. He subdued the lustful thoughts that resurfaced whenever he studied that beautiful body for too long. Dean slowly leaned forward, waiting anxiously for Smith to say something else. He had no idea why he had been called to the side of the tank, and didn’t really have any desire to acknowledge Marshall at all. Dean never knew what to expect from this man he had learned to despise. He would constantly switch from hostility to pacification, and Dean just found it all very confusing. Whatever he did, he always did for Castiel because he thought that was what he wanted so they could stay together. Castiel could see Dean was very nervous. His fingers were flexing in agitation, tail moving backwards and forwards against the base of the tank. His lower fin gave a small tremble when Smith moved closer.

“What’s my name?” Marshall asked, attempting a weak smile. Dean blinked.

“Smith.” Dean replied, in that familiar broken tone Dean always had when he tried to form softer sounds. Marshall nodded, accompanied by an unpleasant twitch at one corner of his mouth. He reached one hand forward in an attempt to pet Dean’s head. “No touch!” Dean cried, suddenly pulling away and pouting spectacularly with displeasure. Castiel almost laughed.

“Oh, he is a feisty one.” Marshall seemed to be taking Dean’s rejection more lightly than Castiel expected, and that actually unnerved him more. It was like he was trying to gain his trust, and Castiel had serious misgivings about any reason for the sudden change. “Come here.” Marshall commanded, gesturing for Castiel to join him by the side of the water. Castiel instinctively reached out for Dean. He swam up to him, rubbing his face against Castiel’s palm. Dean was humming with pleasure while Castiel stroked the soft skin of his cheek with trembling fingers.

“Well. I would say you will prove very useful to me tomorrow.” Marshall headed back towards the corridor. “I thought as much. Goodnight, Castiel.” He smiled, quietly shutting the door behind him. Castiel inhaled a deep breath of relief when he heard Marshall’s footsteps retreat. He quickly flicked the lock shut and put out his arms for Dean to allow him to lift his body out the water.

“Okay?” Dean asked, with wide eyes. Castiel smiled at him, nodding when Dean wrapped his arms around his neck.

“Yeah.” Castiel sighed. Dean had done everything that had been asked of him. It wasn’t his fault Smith couldn’t make up his mind about what exactly it was he wanted from him. “You did real good, Dean.” Castiel answered, gently kissing the top of his head before carrying Dean back to bed. Castiel knew he was being selfish, but now he was even more aware how little time they had left.

Castiel made sure Dean was comfortable. His tail securely placed on top of the sheets while Castiel started to undress. He quickly stripped down to his t-shirt and boxers, eyes resting on Dean the whole time. He was staring up at Castiel with the same wonder in his eyes that was always there whenever Castiel was close. Castiel loved the way that made him feel. He wanted it to last forever, but it was an impossible dream. He knew that now.

“Come. Bed.” Dean encouraged, stretching out his fins in a gesture of submission to his mate. Castiel didn’t appreciate the significance of the display, but understood the request for him to lie down. He lifted up one corner of the sheet and slid in next to Dean. Castiel instinctively reached out to wrap one arm around Dean's waist, settling his fingertips on the line of scales that separated his tail from the rest of his body. Castiel snuggled up close, letting Dean absorb his warmth. Dean pushed the curve of his tail back, and Castiel could hear himself groan at the sensation when Dean moved against him. He wanted so much to touch everywhere Dean would let him. Castiel slowly started to stroke down the smooth spread of upper scales with gentle motions. Dean felt unnaturally cold so Castiel pulled him even closer, rubbing his hands more vigorously over Dean's body to try and warm him up. He crooked one leg over the middle of Dean’s tail, making sure he was completely enveloped in the haven of soft bedding. He wanted Dean to feel safe in his arms before he made any attempt to initiate more of the contact they shared earlier. Castiel needed him so badly.

He couldn’t even think about letting go, but he had to.

“Dean.” Castiel murmured against the fluffy cocoon of damp hair. “I have to go out tomorrow, I have to meet someone.” Castiel tried. He could feel Dean tense against his embrace. His breath hitched when he inhaled.

“Go?” Dean asked, without looking up. “Why?”

“I have to. I have to get you home before it’s too late.”

Dean didn’t say anything more. Castiel wasn’t sure if it was because he didn’t understand, or because he didn’t want to talk about it. Castiel fought back a surge of emotion, trying to distract himself by running the tips of his fingers up and down Dean’s back. He could feel the bones of Dean’s spine pushing against the tips when he moved his hand up towards the base of Dean's neck. Castiel lifted up the sheet so he could take a better look. He could see a few dry patches of skin where some of the surface layers had started to flake away because Dean had spent too much time out of the water. Some of the lower scales were losing their brilliance, and there were small areas of discolouration that were a testament to his confinement in such an unnatural habitat.

Dean was sick.

Castiel pressed his lips together in pain when he held on to Dean and breathed in his scent.

_Tomorrow._

Castiel thought sadly to himself when he closed his eyes.

_Tomorrow, Dean would go home._

_______


	23. Bonding

**Summary for the Chapter:**

> Castiel answers the claim when Dean finally makes it clear a deep commitment to each other is something he has longed for since they were children. They complete their bonding and there is no going back, but Dean starts to get sick again. Castiel beats himself up that it really is all his fault.

**Bonding**

Dean seemed to sense something was wrong. Castiel was holding him so tightly Dean could feel hot air skimming across the back of his neck, so different from the soft breaths Castiel usually exhaled when they were close. Dean curled his body around him for comfort. Castiel still had his eyes shut, but Dean knew he wasn’t asleep. He hadn’t completely understood what was whispered to him when he climbed into bed, but he knew the word _home_ and wondered what Castiel was looking for when he examined his back. Castiel had taken off everything apart from a t-shirt and his shorts, so Dean assumed that meant he was allowed to touch him again. He tried to get Castiel’s attention by stroking searching fingers across his cheekbones, leaning in to brush his lips against those dark eyelashes. They fluttered open when Castiel eventually looked up. Dean thought those beautiful blue eyes didn’t seem to shine quite so brightly anymore.

“Sad.” Dean murmured. Castiel forced a weary smile while Dean ran searching fingertips over his face.

“I’m okay.” Castiel lied. He didn’t want Dean to know it felt like he was dying inside. Their time together was slipping away and now he was really concerned Dean was getting sick as well. Castiel returned the small gesture of affection, running his hand along the skin at the top of Dean’s arm. Dean pressed his fins flat against his body for the second time, but the implication of what he was offering was still completely lost on Castiel. Dean tried again to entice him in the same way he had earlier, secretly hoping Castiel would start to answer the claim like he had before. If he was going home, then at least Dean wanted to make sure they were mated like he might somehow persuade Castiel to go back with him. Dean hadn't even considered how impossible it would be for either of them to be drawn into a different world. Castiel couldn’t possibly live in the water, and if Dean stayed he would never be safe from people like Smith. Dean trailed the edge of his fin along the line of Castiel’s legs and leaned in even more. He was making small keening noises designed to show any potential mate he was willing to submit. Castiel was so distracted by his broken thoughts, he didn’t seem to notice how receptive Dean was to his affectionate touches until he caught the hint of musk in the space between them. Castiel suddenly stilled, unsure just how much resolve was left in him. He was weary and heartbroken, and his will to constantly fight the desire he had for Dean was quickly fading. Castiel had spent his whole life doing what was right and ultimately it had all been for nothing. Castiel tried to protect Dean all these years, and it still ended in tragedy.

Castiel watched Dean spread out onto his back, flexing and curving his tail while he fluttered his fins before finally pressing them flat against his shimmering body. Lubrication was leaking from every pore with one last desperate attempt to give himself to Castiel completely and declare their bonding before they were separated again. Castiel gazed in awe at the captivating display Dean was giving him, eventually realizing all his efforts were just an attempt to seduce Castiel and tempt him closer. It stirred something primal inside him. Whatever this was between them, was something that ran much deeper in them both than he ever expected. It didn't take much for all his noble intentions to fall away.

“Beautiful.” Castiel whispered tearfully, eyes drawn to the graceful sway of fins when Dean ended his courtship ritual. He finished with a submissive posture, tail pushed back behind him. The ends were resting across the top of his back, forcing Dean's hole to stretch open. Ready for Castiel to take him. Dean's hands were clasped together behind him, waiting for Castiel to finally accept him as his mate. Castiel could hardly breathe while he watched the pulse of pheromone slide out. Dean's body was preparing to accommodate the thick length of Castiel’s cock, now pushing relentlessly hard against the front of damp shorts. “Dean.” He breathed. “Are you sure?” Castiel was losing control fast when the combination of heady scent and the thought of finally being able to sink into the warmth of Dean’s body became too much. Dean's eyes never left Castiel’s face when he arched his back to present the full swelling just above his entrance.

“Want.” Dean said quietly, gazing up without blinking. He was hesitantly biting into his lip, and Castiel could just see where the skin dipped in underneath the sharp points of his teeth. “Want you.”

With those words, Castiel felt himself sink forward, dropping his hands to Dean’s hips. He had waited so long for Dean to actually be able to say something like that. The look of hope in his eyes was enough for Castiel to stop fighting it, exhaling Dean's name in a stream of breathless passion. Castiel pushed his searching mouth against him, letting himself go completely the moment Dean told him what he wanted in words Castiel could finally understand. There was no longer any doubt they both wanted the same thing. The feeling of acceptance washed away all trace of denial and doubt, and Castiel abandoned all self-control. He was finally free.

Dean was encouraging Castiel to touch him with gentle nudges of his tail, humming with pleasure every time Castiel moved against him. He ran his hands along the shining scales that seemed to sparkle in the light as Dean twisted under Castiel’s caress. Dean surrendered completely when he let Castiel dip one finger into the edge of the pulsing hole that was now a mess of aromatic slick. Dean shuddered as it entered him and lifted his body up, trembling with the new sensation. Castiel used his hand with skillful precision, hurriedly slipping off what was left of his clothes while he eased another finger in. He started to press his body against Dean’s side, watching the movement of his hand inside him. Castiel couldn't hold back the lust-filled moans that spilled from his lips at the sight of Dean lying helpless beneath him. It was the most beautiful thing he had ever seen. Castiel wanted that moment to last forever. The cruel images and thoughts of Dean returning to the ocean were violently pushed from his mind when he gave in to the desire, wrapping one leg around Dean’s tail while he slid his fingers in and out. The intoxicating scent quickly filled the small room and the sounds of their heavy breaths mingled in the air while Castiel guided his damp body over Dean, mounting him as they prepared to mate.

Dean seemed blissed out and oblivious to all else, when Castiel pulled his hand free and reached down to wrap it excitedly around his own cock, fumbling in the darkness to line up the tip with the enticing space he longed to plunge into. He hesitated for a moment to make sure Dean was ready before he eased in slowly with a moan of want that reverberated from deep inside his chest. Dean forced his tail upwards. Castiel could feel the warm slide into Dean’s body up to the base until his hips were touching the ridge of lighter scales that stretched towards Dean's stomach. Castiel stuttered, desperately trying to keep calm. His blood seemed to be pumping so fast he could hear every beat as it pounded from his heart and surged through his veins. Nothing in his life ever felt so right as that moment, and he couldn’t remember anything else while he thrust hard into Dean with a passion he never believed possible. Dean squirmed and mewled beneath him with every fresh intrusion, back almost bent into a complete arc as the thick muscle of his tail was pushed forward so he could take Castiel in completely and surround him with the tight heat of his body. Castiel was panting with exertion by the time he was almost at the edge, emptying into Dean with everything he had.

“I love you.” Castiel murmured. The ecstasy had captured all his senses, words passing his lips before he even thought about what he was saying. As if in response, Dean tipped his head back as they completed their bonding, letting out a long high note that seemed to thrum across his throat when it pierced the air. Castiel collapsed on Dean’s chest, curving his hands around the side of the slippery body while he gasped in dry breaths, shivering at the sudden cold that brushed across his skin. Castiel lazily pulled the sheet over them and snuggled up close to Dean. They held each other tightly until their hearts beat perfectly together. “I love you, Dean. I always have.” Castiel whispered, closing his eyes again so he could let sleep take him.

_____

Castiel woke up to find they were stuck together in the mess drying between their bodies. He smiled to himself, turning to look at the peaceful face of the love he had finally taken as his own. Castiel may not have completely understood how significant what they did the night before was to Dean, but guessed he had answered the claim by physically bonding with him and telling Dean how much he loved him. Castiel wasn’t even sure Dean knew what human love was, but he intended to show him. Castiel made a fateful decision. He was going to meet with Shaw and tell him he'd changed his mind. He was going to stay with Dean. Always. Somehow, he would find a way.

Castiel tried to rouse Dean from sleep with a gentle stroke of his fingers across Dean's shoulders, but he seemed unresponsive and unnaturally cold again. The room was warm enough through the night, stealing the heat from each other’s bodies when they curled up beneath the sheets after mating.

“Dean.” Castiel smiled softly when the memories returned and spread down his body. He felt another sudden twitch between his thighs, hoping they might have time to make love again before he had to leave or got disturbed by one of the others. Dean looked to be sleeping so deeply Castiel was almost reluctant to wake him, but he didn’t want them to get caught before they had time to escape. He needed to make sure he would be able to get Dean far away from the institute and the coastline. He hadn’t even come up with the semblance of any viable plan, but he wasn’t thinking about the consequences. Castiel had finally admitted his love for Dean, and there would be no going back.

Castiel tried again with a gentle shake of Dean's arm where it was resting on the sheet. Castiel frowned when he leaned in to examine Dean's skin more closely. He realized the patches of discolouration had now spread to parts of his upper body, and there were angry marks where thin layers of the top skin had peeled away completely. He pulled Dean’s body towards him and felt his back. It was damp with perspiration and the oily residue Dean secreted when he was preparing to bond with Castiel the night before. Castiel could feel a small curl of panic start to twist in his stomach while he waited for Dean to open his eyes. He called his name more loudly, trying to shake him awake with much more force than he used before.

Castiel instinctively put his head against Dean's chest, almost weeping with relief when he could still hear his heart beating under the skin. It was faint and slow, but it was there. Castiel felt across his brow and the sides of his face to see if he had a fever. Castiel sat up and pulled the sheet free before turning on the lamp so he could study Dean better. He felt ill when his eyes scanned the length of that rigid body. His scales were unusually dry, their natural luster almost faded completely. Some of them had come loose and were jutting out at strange angles like they were about to fall. His beautiful skin had lost its subtle hue and looked almost transparent in places. Castiel thought he could see lines of stiff muscle tightening underneath the skin. His thoughts were a disjointed mess of unanswered questions.

_Had he done something to make this happen? Maybe they shouldn’t have completed the bonding. Was it because they were different?_

Castiel was filled with guilt again, wondering sadly if this was all his fault as well. A dreadful realization suddenly struck him hard. Dean wasn’t just sick. He was dying.

_____


	24. Sickness

**Summary for the Chapter:**

> Dean's sickness appears to be getting worse. Castiel now fears for his safety so much, he makes an impulsive decision to make their escape before anyone can stop them. Castiel intends to stay with Dean forever, but when they reach the water he realizes it was just an impossible dream.

**Sickness**

Castiel felt like his heart might stop beating altogether when a surge of anxiety rose up through his body and clawed at his throat.

_He had done this._

His selfish desires kept Dean out the water for too long. Castiel guessed all the abuse Dean's body had suffered during the hours he spent downstairs had scarred him in ways he couldn’t even bear to think about. Castiel stroked his hand along the dry tail once more, gasping when one of the upper scales came away and caught between his fingers. He instinctively tried to stick it back on but it just fell away, dropping into the mess of dried slick and semen that leaked from them both when they mated.

Castiel got up, holding Dean in his arms while he pushed the dirty sheet away. He moved as quickly as he could with such a dead weight before carefully lifting Dean up to the edge of the tank. He draped the tail fin over the side first, swiftly gathering up a handful of water to trickle over his scales. Castiel rubbed it between the gaps in a desperate attempt to relieve the obvious dehydration making Dean so listless. He stirred while Castiel held him over the water, eyes flickering under their lids while it got absorbed into his skin. Dean was still lying heavy and unresponsive. Castiel repeated the gentle motions until he knew he couldn't hold him up any longer. He had to let go, hoping Dean would be able to swim once he was submerged. Castiel carefully pulled his arms out from under him and watched Dean's body drop to the bottom of the tank like a stone. Castiel called out frantically to Dean, but he was completely still. Castiel squatted down next to the base of the glass. He could see Dean's eyes were closed and no bubbles were coming from his mouth. The gill slits were pressed flat against his neck.

Castiel cursed and called to him again several times, but he got no response and now he knew Dean wasn’t breathing. He quickly pushed himself up and over the side of the tank without thinking. His only thought was getting to Dean. Castiel disappeared under the water with a loud splash and propelled his body to the bottom, pulling at Dean’s shoulders to turn him over. He eventually managed to heave Dean up to the surface, holding him close against his chest. Castiel rubbed hard at his skin to make Dean take a breath. He softly kissed the cold lips, whispering encouragements against his mouth while he stroked the line of his gills to try and get them open.

After a few long seconds Dean spluttered, a stream of water springing from his mouth with a rush of air. The slits on his neck trembled, opening and closing wildly as he came back to consciousness. Castiel inhaled a deep breath of relief and continued to caress him. He could soon feel the warmth slowly return where Dean's body was pressed against his chest.

“Thank God.” Castiel whispered. Dean still looked pale and the light seemed to have left his eyes, but at least he was awake and taking in enough air to be able to breathe on his own. He was very confused, glancing around the room with searching eyes. “I’m so sorry, Dean.” Castiel murmured, cupping the side of his face with one hand. Dean leaned into the touch, faint hint of a smile pulling at his mouth. “You were out of it.” Castiel soothed him with a sweep of one thumb across his cheek. He wasn’t sure Dean understood, so he just asked him if he was okay and Dean gave a little nod. Castiel suspected that was far from true.

Castiel waited with Dean in the water for a few more minutes until he was certain he would be alright on his own and tentatively released his hold. Dean didn’t swim away, but Castiel was glad he didn’t sink like before. Castiel climbed out the tank, eyes resting on Dean the whole time. He was still very concerned, now even more reluctant to leave him alone with Smith while he went to meet Shaw. Getting Dean away from the institute was becoming more urgent with every minute that passed. Castiel hardly dared to go anywhere without him, but he needed to get out and discuss the escape plan. He knew Smith had something terrible planned for later that day, and Dean was too sick to be subjected to anything at all. The idea the man he loved might be abused and tortured was beyond detestable. Castiel made an impulsive decision he may regret, but he was running out of options. It was still early in the morning. There was no sound coming from the lower halls, and he was fairly certain there would be very few staff in the building at all unless Smith had arranged for someone to watch them. He had to chance it.

Castiel quickly tapped out a message to Shaw explaining they would have to meet much earlier than planned, hoping he would get it in time. His fears were unfounded when he got a reply almost immediately. Shaw must have been expecting it. He told Castiel he would come straight away, but it would take him at least half an hour to reach the coast. Castiel packed up some water bottles and a blanket in his backpack, trying to figure out the quickest route to the main entrance without being seen. He had all his ID, keys tucked safely away in the bottom of his pocket. He wouldn't be coming back. Castiel hurried to the closet in the bedroom and quickly checked his jacket, breathing out a sigh of relief when his fingers brushed against the key card that would open the front door. He called to Dean on his way back through the apartment, signalling for him to come up to the top of the tank. He still looked pale and weak, but Castiel was certain his health would improve as soon as they got him back to the ocean. He had no idea how he was going to stay with Dean, but it was the last thing on his mind right then. The need to get him free at all costs kept echoing in his head. Castiel held out his arms to Dean. He immediately fell into them and let Castiel haul him over the side. He hitched up the pack and wrapped his coat around Dean’s shoulders to keep him warm and hide him from view.

Luck was with them as they scurried along the dark corridors. The building was quiet. Castiel didn’t see anyone at all as they headed down the main stairs, fighting the burn in his muscles. He held Dean close and quickly descended the steps. His heart was beating so fast he was frightened someone might hear it, but he pressed on, draping Dean over his shoulder so he could scan the lock. They stepped outside, fresh sea breeze skimming across their faces like a caress. It felt wonderful. Castiel carried Dean down to the beach. He stirred restlessly when he realized what was happening. Dean clutched his sharp claws into Castiel’s shirt with a soft gasp of surprise.

“No.” Dean cried suddenly, trying to push Castiel away so they would have to stay on the sand.

“Dean, it’s alright. It’s okay - I’m not leaving you.” Castiel whispered, gazing into Dean’s eyes. He just looked sad and confused. Castiel was desperate to explain it all, but there was no time. “I need to get you back in the water. I want to come, I want to be with you.” He hoped Dean could understand, stroking one hand along his tail where it hung limply across Castiel's stomach. Words were just spilling out. Castiel had no idea how he would be able to make good on that, but he would think of something.

By the time they reached the waves, Castiel heard a truck screech to a halt on top of the cliff. He saw Shaw leap out and start to run towards him. He was waving frantically, pointing along the sea to the right. Castiel gazed in amazement when he saw two lithe figures gliding towards them. The smile of recognition that graced Dean's face was beautiful. He encouraged Castiel to let him down, shuffling across the sand to the foam breaking at Castiel’s feet. Shaw reached him by the time Dean’s tail was submerged.

“Castiel.” Shaw gasped. “You did it, he’s free.” Castiel nodded, but he didn’t smile.

“I know, I’m going with him.” Castiel replied breathlessly. Shaw placed one hand sympathetically on Castiel’s shoulder.

“Castiel, that’s not possible. How can you go with him? What were you thinking?”

He had let his emotions cloud his senses. Shaw was right, it was impossible. He hadn't really thought about it at all. His desire to be with Dean caused him to lose his already tentative grip on reality. Dean was swimming over to the mermaids waiting for him in the shallows. He looked longingly at Castiel while the waves washed over him.

He understood they would have to part. Dean had to leave his mate forever. The pain in his heart was indescribable.

Castiel sorrowfully watched the graceful movement of sleek bodies while they circled Dean. The male one was moving closer with each dive, playfully flicking his tail against the water. Even with the noise of the wind blustering around him, Castiel could hear the high pitched calls and clicks that issued back and forth between them. They were going to take Dean with them. Castiel sank to his knees in the wet sand. His eyes filled with tears, but the breeze dried them before they had chance to fall. He gave Dean up once already so he could be safe and that hurt, but nothing could compare to the crushing agony he felt now. It was like someone just ripped his heart from his chest with so much force it took all his breath away. Castiel couldn’t move or speak. He just stared out across the grey ocean while Dean slowly began to swim away. He passively followed the others around the curve of the coastline jutting out in the middle of the water, but he was always a few metres behind them like he was waiting for something. Castiel blinked through blurry eyes while he tried to take in every last detail until Dean eventually disappeared from view. Castiel wanted to hold the image of his beautiful silhouette in his head forever.

Castiel dug the tips of his fingers forcefully into the sand, swallowing down the raw sobs that threatened to spill from his mouth. The waves continued to roll in towards the shore like Castiel wasn’t even there. The constant shift and swell of the tide cared nothing for the broken heart of a solitary figure watching the movement through dull eyes. He had to go home. He would have to move out of the institute. Castiel didn’t want to face explanations he would be forced to give when they caught up with him. He had already written his resignation letter and left it at the front desk, feeling nothing when he walked away from that place for good. No sadness in leaving, no regrets. Just numbing pain for a loss that would take a lifetime to fade. Maybe it never would. Castiel closed his eyes, inhaling a gasp of fresh sea air when he stood up to brush the sand away. The salt scratched at the back of his throat and made his eyes sting, footsteps faltering all the way back up the beach. He never felt so alone.

_____

Two days had passed since Dean was forced to leave him, and Castiel hadn't eaten a bite of food or slept for more than an hour at a time. He felt constantly sick. All his thoughts were consumed by images of Dean’s face, his smell, the way he breathed his name against warm skin in that fragmented way Castiel loved so much. He wiped the perspiration from his brow, restlessly shifting between the sheets. His bed felt so cold and empty without the smooth slide of a tail against his legs. He missed those deep green eyes that always gazed at him like he was worth something. His only comfort was knowing Dean was safe.

Castiel would never forget him. The last twenty years spent trying to convince himself his own life actually meant something without Dean were dismissed in an instant.

Dean _was_ his life.

Castiel must have drifted off again while that thought still consumed every corner of his mind. He was woken to the sound of his cell, dropped carelessly on the floor next to his bed. He had no desire to talk to anyone. Castiel aimlessly reached for it, opening it up before even looking at the screen.

“Hello?”

“Castiel?” Shaw’s voice resonated through the darkness. Castiel could hear a hint of concern. Panic soon startled him fully awake.

“What’s the matter?” He asked quietly, heart thudding relentlessly behind his ribs. He knew Shaw never called unless it was about Dean, and couldn’t imagine why he would be ringing so late. Dean was beyond their help now and Castiel didn’t want to think any more about that, especially in the middle of a lonely night.

“I’m sorry if I woke you, but I thought you should know.” Shaw continued hesitantly.

“What? What happened?” Castiel's mouth was unnaturally dry. He could hardly get the words out.

“I’m not sure I should be telling you this, but it’s about your mermaid - ” His voice trailed off uncertainly.

“Dean?” Castiel stuttered. “What do you mean?” A stab of anger and hurt betrayed his voice. It was cruel to torment him with the reminder of what he lost. “You know Dean’s gone.” The words cut into his heart when the fleeting memory of their last goodbye on a desolate beach surfaced in his mind. He heard Shaw sigh. 

“No, Castiel. He wouldn’t leave.” Castiel gripped the phone so tight, the edge was digging into his palm. He was breathing fast, unable to force out a response at all. Shaw continued anyway. He must have sensed it was a lot to take in. “The others had to go. They already waited too long and the water was getting much colder as it was. Your mermaid… Dean.” Achak corrected respectfully. “I think he must have refused to go with them. I went to say goodbye and wish them well, but when I got there they seemed to be having quite a heated discussion. He just kept saying your name.” Castiel swallowed hard around a tightness in his throat.

“What happened?” 

“Eventually they left. All of them at first, but your Dean must have come back. I saw him head back up to the cove this evening just before sunset. I wasn’t going to tell you but - ” Shaw paused. “He must have stayed for a reason. I think he came back for you.” 

“Why would he?” Castiel began, but Shaw hushed him.

“Don't worry, your secret's safe with me. You love him, don’t you?” Achak asked suddenly. It was such an unexpected question, it caught Castiel off-guard. Making him pause before he could answer.

“Yes.” Castiel admitted at last. “I love him more than anything.”

“He’s all alone down there.” Shaw said gently. “Alone, and cold and probably scared half to death.” Castiel was fighting the burning urge to run down to the beach in nothing but his shorts and gather Dean up in his arms. Logic wanted to leave Dean alone long enough to make him think Castiel wouldn't come, so he would eventually follow his pod. “Castiel.” Shaw sounded happy. Castiel imagined he might even be smiling. “Why the hell are you still talking to me?”

Castiel blinked, snapping the phone shut without even saying goodbye. He pulled on his clothes and headed out the door without a coat. He had just one objective. 

Dean.

Castiel didn’t even know what time it was, and he didn’t care. He wanted Dean so badly his body ached. Castiel ran down to the car and set off up the long dusty coast road towards the bay.

“It’s okay, Dean.” He murmured to himself, heart fluttering happily in his chest at the thought of seeing his mate again. Castiel wanted to kiss every last inch of him. “I’m coming.”

_____


	25. Peace

**Summary for the Chapter:**

> Castiel must reach the cove before it's too late and rescue the man he loves from a lonely fate. With the help of a friend, Castiel manages to get Dean to safety but they have nowhere to go so they can stay together. Castiel knows he can never leave Dean again, swearing this is the one promise he will keep.

**Peace**

The dark seemed to close in around him when Castiel raced along the edge of the mainland. He paid no heed to the speed limits, taking the corners so recklessly he was lucky to stay on the road at all. His thoughts were consumed with the need to get to Dean, desperate to know why he didn't follow the others back out to sea and join the pod before they set out for warmer waters for the winter. Castiel hardly dared to hope Dean loved him in return. Castiel thought they already said their last goodbye, spending two days trying to push down the impossible pain he felt since Dean was forced to leave him stranded on the sand alone. Castiel embraced the warm hope there really might be a way they could stay together. His heart sank again when he had to dismiss the idea just as quickly. It was a decision he had no right to make.

Castiel rubbed his hand across his eyes. He was tired, his body ached, and the many miles still to drive stretched out before him. Every second that passed was another one without Dean - another wasted. It took almost an hour to reach the path leading down to the isolated cave where Dean might be hiding. Castiel wasn't sure how much Smith might have guessed already or figured out on his own when he realized Dean was gone. He could only imagine how furious he would be at Castiel’s betrayal. Part of him wondered if he would come after them just to try and take Dean away from him again. Not once had his former friend ever cared about how Dean felt, acknowledged what he did to him was wrong. Castiel waited until he was certain he was alone, hoping he hadn't been followed when he walked away from the car, scanning the bleak landscape in every direction.

Castiel was slipping down the steep bank when he heard a muffled call behind him. His breath caught in his throat, turning to peer through the darkness. Relief flooded through him when he recognized the sway of sleek black hair shining in the moonlight as Shaw approached.

“Achak.” Castiel gasped. He didn’t usually call him that, but he was so pleased to see him the moment seemed much more intimate somehow. He would never be able to repay that man for everything he had done to protect them both.

“Castiel.” Shaw smiled. “I knew you would come.”

“I had to.” Castiel replied. Achak let his gaze drift over to the shoreline. “It’s been - ” Castiel searched for the right word that wouldn’t leave his heart open and vulnerable. “ - rough, since Dean left. Honestly, I never expected to see him again.” Castiel trailed off, a blush touching the top of his cheeks. It seemed strange telling someone else how much Dean meant to him, but it didn’t feel wrong. He knew Shaw understood. They both wanted the same thing. To keep Dean safe. Shaw knew Castiel would never let anyone hurt him again while he had a single breath left in his body. Castiel shook himself back to the present, running one hand through his hair while he shuffled his feet in the dust. “So.” Castiel asked quietly. “Why did _you_ come?” That didn't really come out like he meant it to. “It’s just… you’ve done so much already. I can’t ask you to risk any more for me, _for us_.” Castiel added quickly. The sound of it sent warmth rushing through his chest.

_Us._

“It’s my honour. I want to help.” Shaw replied, nodding for Castiel to go on down the cliff without him. “I’ll be right here if you need me.” He offered kindly, patting Castiel’s shoulder before walking back to the top of the road to wait. Castiel inhaled deeply before setting off down the slope to the sea. The tide was high, and he could hear the waves breaking somewhere down below him. The water must have almost filled the small cove by now. It was possible Dean could have already swum out into the open ocean. Dean didn’t know Shaw had seen him return, and that was something that still puzzled Castiel. If Dean really had come back for him, he would have no way of letting him know.

 _No_. Castiel told himself sadly. There must have been another reason why Dean stayed. He swallowed down the bitter truth and continued to slide down the bank, grasping at the thick tufts of marram grass to help him stay upright. He sighed with frustration when he reached the base of the rocky ledge. The edge of the water was lapping up the sides, and the way to the cave entrance was almost completely blocked. Castiel could see the dark arch where the rock was worn away, waves covering the base as they flowed in and out of the opening. He watched the movement of water for a few seconds, trying to judge the depth of the shallows. It looked too deep to wade across, but the thought of Dean being alone and cold inside the dark hollow was too much.

It tempted Castiel towards the dangerous swell beneath him, casting aside all fear and caution when he hurriedly slipped off some of his clothes and jumped into the water. It was much colder than he anticipated, knocking the air out of his lungs when he hit the surface. He started to wade forward, completely drenched and shivering relentlessly by the time he reached the hidden shelter of rock. Castiel was panting with exertion, and could hardly walk without stumbling when he pushed through the breaking foam, almost throwing himself on the floor of the cave. It was eerily quiet and too dark to see anything other than moonlit silhouettes illuminated by a small rift in the ceiling. His heart was beating insanely fast as he peered into every corner in search of his beloved Dean. Castiel called out to him through the blackness, forcing his way through the advancing tide until he reached the back wall. His fingers traced hesitantly along the jagged rock, his eyes wide and sharp. He was almost on the edge of believing Dean must have already left with the tide when he noticed a still figure curled up in one corner.

Dean.

“ _Jesus_.” Castiel breathed, running over to him and bending down next to his body. Dean was curled over with his back leaning against a small outcrop, tail partially submerged in the water. It swayed back and forth with the ebb of the tide but the upper half of his body was pale and unmoving. “Dean.” Castiel called again, gently stroking his palm along the heavy muscle of his tail. Castiel caressed his face, reaching out to pull Dean into his arms. Castiel rocked Dean slowly while he smothered him in desperate kisses. He rubbed and pawed at Dean’s skin like he would never be able to let him go. Castiel pushed the damp hair away from Dean's face. His cheeks looked hollow, skin clammy and cold. The sickness in him obviously hadn't improved since his return to the water, and Castiel thought that was probably because he hadn't been back out into the deeper trenches. Dean couldn't swim properly and had eaten nothing over the last few days. There wasn't any sign in the cave to suggest he had done anything at all. Castiel’s heart almost stopped when he realized why Dean had come back. He wasn’t waiting.

He came here to die.

A surge of raw emotion was forced up inside Castiel. He was suddenly gasping through loud broken sobs that echoed in the small dark cave. He couldn’t seem to make it stop. Everything he had been keeping locked away came flooding out in waves.

Sadness. Sympathy. Shame.

Castiel was trying so hard to accept they couldn’t be together, but the thought Dean would rather stay here and give up his life than be without him sent Castiel over the edge of despair. He held Dean close and breathed against his skin. His tears slowly subsided. He felt Dean shift in his embrace, and Castiel pulled back just enough to see his eyes flicker open. His expression was blank and emotionless when he stared back up at Castiel like he didn’t believe he was really there - that he came back for him. Beautiful green eyes were full of doubt and confusion. Maybe he thought Castiel was just a cruel illusion sent to torment him in his final moments.

“Cas?” Dean stammered weakly, cautiously lifting up a weary hand to scrape his knuckles against Castiel's jaw. His eyes sparked back to life when he realized the man he loved was holding him in his arms.

“Yes, Dean. I’m here.” Castiel comforted. His own voice sounding so lost and broken, he just cradled Dean even tighter and wound their fingers together. He brought Dean’s hand up to his mouth, reverently kissing along the line of each fingertip. Dean was still so weak, Castiel had to carry him all the way out into the water. He called for Shaw to help him. The desperation in his voice must have been unmistakable because the man appeared almost immediately at the top of the path. He was leaning over the edge, one hand shielding his eyes from the flurry of bitter spray that assaulted him as the waves crashed against the rock.

“Shit… what’s the matter with him?” Shaw gasped, eyes wide with the sight of Dean lying limp in Castiel’s hold while he struggled to push his way through the breaking tide.

“He’s still sick. Help me, please.” Castiel called up. Shaw didn’t hesitate, and scrambled down the dunes. He reached out one arm as far as he could without falling, wrapping his other hand tightly around a cluster of grass to anchor him.

“Come on, just a little further.” Shaw shouted, through the noise of the roaring breeze coming in from the sea. Castiel forced his body to keep going until he could see the tips of Shaw’s fingers in the darkness. He steadied himself, gesturing for his friend to catch Dean when he threw him forward. They would only have one chance. If they failed, Dean would land in the water and be pulled under or have his body broken on the rocks below. Castiel bit hard into his lip, forcing every last scrap of energy he could find into the burning muscles of his arms and propelled Dean forward. Castiel fell into the water and got dragged below the surface before he even had chance to catch his breath. 

He spluttered when he came up, swimming in forceful strokes to the edge of the sea to haul himself up on to dry land. Castiel rolled over onto his back and sat up, not sure if Dean was safe. He released a rush of air in relief when he saw Dean curled up next to Shaw on the bank. He was covered with his coat. Together they managed to lift Dean into the truck. Castiel abandoned his car and sat in the back with Dean laid across him, head resting in his lap and his tail curled around Castiel’s legs like he never wanted to let him go. Dean snuffled sleepily against his side. Even in the dim light Castiel could see the side of his mouth curve up into a blissful smile.

“What can I do?” Castiel asked quietly, his eyes fixed on the chocolate brown gaze staring back at him from the rear view mirror. “I don’t know what to do, where to go.” He stammered. “I can’t, I won’t - ” Castiel corrected. “ - leave him. Never, never again.” He set his jaw in determination and wrapped both arms around Dean while he made that promise. Shaw nodded silently before glancing back to the road.

“I know.” Achak replied at last. “I wouldn’t want you to.” Castiel's features were all scrunched up when he frowned, desperately trying to think of somewhere they could go and still stay together. He couldn’t even contemplate the alternative. His place was at Dean’s side. Castiel was going to love him. Love him, and cherish him, and make him get well again. There was a heavy silence while the truck continued to bump along the coast. “Actually.” Shaw said slowly. “I think I have an idea.”

_____

Back at the institute, Smith could hardly contain his anger when he read the letter Castiel left on the front desk, along with his folder and a substantial stack of paperwork that constituted his record of the project.

** MBRI **

** Research Log **

Research Associate Professor

Dr. C. Milton. MSc (Marine Biology)

**Final Entry**

This is my final entry. I have resigned from the institute and will be leaving the state of Maine as soon as possible. I have been forced to cancel the Aquatic Ape project since it has come to my attention all sightings were part of an elaborate hoax by a local fisherman intending to profit from the scheme. Witness statements have subsequently been dismissed and the taped evidence has been identified as a fake.

This particular mermaid legend appears to have originated from a local native tribe, and has no basis in fact. No scientific evidence has ever been found to suggest such a creature has ever been observed off the coast of Maine.

They simply do not exist.

Castiel Milton

“Son of a bitch.” Smith cursed. He hadn't given Castiel enough credit for his devotion to Dean, and now he would never be able to find them. His house still stood empty and all records of his work mysteriously disappeared from the computer. No more hard copies would ever be found. Marshall sighed, dropping the file on the desk before he walked away.

Project closed.

**_____**

**Epilogue**

Castiel watched Dean twist his beautiful body through the cool water of Great Lake. It was six in the morning and his ritual never changed. Castiel was so protective of him, even now. Almost two years had passed since the fateful day he rescued Dean from the facility in Maine. He always made sure Dean bathed early before each new day began to make sure no one ever saw him. Castiel thought it probably wouldn’t have mattered here anyway. Not a single one of the people who lived on the reservation would ever have given them away. Castiel wanted to watch Dean move through the blue water again, just as captivated by his grace and beauty as he was the first time he ever saw him. Dean paused for a moment and turned on to his back, fluttering his eyes at Castiel while he twirled his tail in small circles and pushed a stream of water up from his mouth. It was still the most seductive thing Castiel had ever seen, and Dean knew how much he loved it so he just did it even more. The sun was rising on a new dawn and washing the surface of the lake with a rosy glow. Castiel was sitting on the wooden dock next to their lodge and dangling his toes in the water while he admired his mate. The modest house on the bank was their home, their safe place and everything they would ever need. Castiel finally realized what was really important in a world they both locked themselves away from forever. Not money, not prestige, not some respected degree from one of the best universities in the country.

_Love._

That was the only thing that ever mattered, and Castiel was thankful every day he had found it with Dean. They were meant to be together. Castiel laughed happily when Dean came in to the edge and put up his arms, just like he always did so Castiel could lift him onto the jetty. Dean melted against him while Castiel carried him back into their little home. The water dripped from the end of his tail fin and made small puddles on the floor, but neither of them cared. Castiel hitched Dean up a bit higher and kissed him forcefully on the mouth.

“Still early, come back to bed.” Dean whispered against his lips. Castiel smiled at how well he had taught him. He could have almost whole conversations with him now, but Dean always seemed to want to show Castiel how much he loved him rather with his hands and his mouth. Words never seemed that important to them. They shared many stories over the years they had spent together, and Castiel finally found out the truth about the last time Dean had come up to the harbour in search of him. It had been the summer of 2004. Dean had waited so long for him, but Castiel never came.

None of that mattered anymore. They were together. Happy. Safe.

Castiel finally found the peace he searched for his whole life. He carried Dean through to their bedroom and laid him down gently before sliding in next to him and pulling him close. 

“Love you.” He murmured against Dean’s open mouth. Dean let Castiel caress him.

“Love you more.” Came the soft reply.

Castiel still adored the fragmented way Dean spoke. He could never tire of hearing it, knowing in his heart they would stay together for the rest of their lives. 

_____


End file.
